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The effect of Ru addition on the martensitic transformation and mechanical properties of Zr50Pd50−xRux SMAs shape memory alloys has been studied. Strain–temperature experiments, differential scanning calorimeter, and scanning electron microscope analyses were performed to validate the theoretical predictions by DFT calculation regarding the influence of the C′ parameter on martensitic stability. Despite the absence of an observed shape memory effect under the tested conditions, the findings suggest that ZrPdRu alloys hold promise for high-temperature applications. [ABSTRACT FROM AUTHOR]

Titanium alloys have broad application prospects in the field of marine engineering due to their excellent corrosion resistance and comprehensive mechanical properties. Titanium alloys, when connected with other metals, such as copper-nickel alloys, could produce two distinct effects. On the one hand, the passive film gives titanium alloys positive potential, which could accelerate galvanic corrosion of negative-potential metals. On the other hand, the passive film could obstruct current flow and prevent further development of galvanic corrosion. In this paper, Potentiodynamic Polarization, Electrochemical Impedance Spectroscopy, and Electrochemical Noise techniques were utilized to investigate the galvanic corrosion behavior of B10/Ti80 under simulated seawater environment. The corrosion morphology and product composition were studied using Scanning Electron Microscope and X-ray Photoelectron Spectroscopy. The above experimental results showed that Ti80 and B10 served as the anode and cathode respectively in the early stages of corrosion (within 2.5 h of immersion), due to the incomplete formation of the passivation film on Ti80. While in the latter stages of corrosion, due to the positive shift of Ti80's potential by passivation, there was a noticeable accelerated corrosion effect on B10, which was proportional to the area ratio of Ti80/B10 and showed a gradually stable trend after 28 days of immersion in the seawater. [ABSTRACT FROM AUTHOR]

In this paper, the microstructure and mechanical properties of Al-6.5Si-5.5Cu-0.2Zr-0.01Sr-0.06Ti-0.2Ce cast aluminum alloys were investigated in multistage solid solution systems. The microstructure of the alloy was characterized using an optical microscope (OM), scanning electron microscope (SEM), energy-dispersive spectrometer (EDS), x-ray diffraction (XRD) and transmission electron microscope (TEM), respectively. The hardness and conductivity of the alloy were measured using a Vickers hardness and eddy current conductivity testers, respectively, and the tensile properties were described by a drawing machine. The results showed that the mechanical properties of the alloy are the worst under the four-stage solid solution system (G1). With the increase in multistage solution temperature and holding time, θ phase (Al2Cu) was gradually dissolved into α-Al matrix to enhance the effect of dislocation strengthening. When the solution temperature reached 510 °C, the mechanical properties of the alloy were the best, and the tensile strength and elongation were increased to 354.90 MPa and 9.02%, respectively. With the increase in temperature, eutectic Si agglomeration and large area of insoluble phase between metals were found, resulting in the decrease in mechanical properties. [ABSTRACT FROM AUTHOR]

Magnesium and its alloys are advantageous in clinical applications due to their excellent mechanical properties and suitable biological properties. However, due to their high corrosion rate in physiological environments, these alloys' application was limited. Polypyrrole (PPy) coatings were potentiostatically deposited on AZ31 alloy to reduce its corrosion rate in this study. The effect of applied potential and monomer concentration on the coatings' characteristics and properties such as wettability, corrosion resistance, and adhesion strength was studied. The coatings had cauliflower and porous micro-granular morphologies, according to scanning electron microscope images. The thickness and average roughness of the coatings increased from 0.3 to 3.8 µm and 18.3 to 43.7 nm, respectively, as the monomer concentration in the deposition bath was increased from 0.1 to 0.2 M. Increasing the applied potential had the same effect on thickness and roughness. According to the water contact angle (WCA) results, the alloy and all of the PPy coatings were hydrophilic. However, increasing the monomer concentration of the bath and the applied potential increased the WCA of the coatings. The electrochemical behavior of the samples in Ringer's solution was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy. All of the coatings outperformed the bare substrate in terms of corrosion resistance. The corrosion current density of the optimum PPy coating obtained from a bath with 0.2 M pyrrole monomer at 3 V was approximately seven times lower than that of the AZ31 alloy. In the cross-cut adhesion test, this coating also demonstrated the best adhesion to the substrate. [ABSTRACT FROM AUTHOR]

Weight reduction is one of the prime goals for auto industries to achieve fuel economy, and magnesium matrix composite offers the opportunity to assist with fulfilling those needs. The present work focuses on developing the magnesium alloy (AZ91D), AZ91D/SiCnp nanocomposite, and AZ91D/SiCnp/CNT hybrid nanocomposite via the semisolid stir casting technique incorporating the ultrasonic vibration process. The produced cast samples are subjected to physical, microstructural, and mechanical characteristics study. The evaluated results are compared and it was found that AZ91D/6wt% SiCnpnanocomposite offers high hardness (78.45 ± 0.1 Hv), yield (150 ± 1.8 MPa), and ultimate tensile strength (241 ± 1.75 MPa) as compared to the cast AZ91D alloy samples. The scanning electron microscope reveals the homogeneous particle distribution structure with reduced porosity. The density of the developed composite obeys the rule of the mixture, and the porosity is limited to less than 1%. The presence of 6 wt% carbon nanotube in AZ91D/6wt% SiCnp alloy nanocomposite facilitates superior hardness, yield, and tensile strength of 84.35 ± 0.1 Hv, 174 ± 1.5 MPa, and 271 ± 1.6 MPa. The impact strength of the composite increased, while the content of SiCnp was improved. [ABSTRACT FROM AUTHOR]

Aluminum–copper-based alloy has a broad liquidus to solidus temperature range, making it susceptible to the formation defects such as pores and shrinkage pores during the process of solidification. Hence, ultrasonic vibration and squeeze casting can help to refine the microstructure and eliminate the formation of pores. In this paper, we used an optical microscope, scanning electron microscope, transmission electron microscope, differential scanning calorimetry, and thermal analysis to study the ultrasonic treatment (UT) and squeeze casting (SC) on the as-cast and heat-treated microstructure of Al–Cu–Mn alloys. The results show that a significant refinement can be obtained by the compound field compared with that of the individual field. The applied UT time is 30 s and 120 s, respectively. The smallest grain size and the finest Al2Cu particles are observed in the alloy with a treated time of 120 s. This is due to the ultrasonic field breaking the dendrites and promoting the flow of molten Al; squeeze casting increases the cooling rate and stimulates the nucleation temperature of α-Al. The size of the θ′ phase after compound field treatment is smaller because more Cu atoms are dissolved in the Al matrix, so the θ' strengthening phase is finely dispersed in the Al alloy matrix. It is concluded that the compound field of UT and SC is a potentially advantageous process to refine the microstructure of Al alloys. [ABSTRACT FROM AUTHOR]

In this work, the influence of pulse frequency in the electric pulse treatment (EPT) on the wear and corrosion resistance of Al-4.5Mg-3Si alloy has been investigated by using a ring block friction tester, electrochemical workstation, stereo microscope, laser scanning confocal microscope, scanning electron microscope, and x-ray diffractometer. Results have shown that the hardness of samples with EPT significantly improved, and the volume of the Mg2Si phase was lower than those of the original sample. And the wear and corrosion resistance of Al-4.5Mg-3Si alloy was significantly improved by EPT. When the pulse frequency was 7 Hz, the maximum hardness was 77.100 HBS, and the volume fraction of the Mg2Si phase was reduced from 38.28 to 33.81%. The self-corrosion potential was increased from − 1.3241 to − 1.2764 V, self-corrosion current density was reduced from 1.2726 × 10−5 to 1.0048 × 10−5 A/cm2, and the lowest average corrosion rate was 113.10 g/m2 h. [ABSTRACT FROM AUTHOR]

The effect of solo and combined addition of Al (3wt. %) and Zn (1wt. %) into gravity-cast Mg-10 wt. % Sn binary alloy on the dry sliding wear test has been investigated using pin-on-disk configuration with varying rotational speed (100 and 200 rpm) under a range of test loads (10, 20, 30, and 40 N). Microstructural characterization and phase analysis of the as-cast Mg-Sn alloys using scanning electron microscope and x-ray diffraction, respectively, have revealed the refinement of the binary alloy microstructure in terms of smaller dendritic arm spacing, uniform and discrete distribution of eutectic phase mixture at the interdendritic locations owing to the alloying additions. Moreover, a significant improvement in microhardness is achieved with increase in amount (wt.%) of alloying elements, depicting the highest hardness in the Mg-10Sn-3Al-1Zn (wt.%) alloy. Simultaneously, the alloying addition even in micro-concentration has been found to reduce the specific wear rate than that of the binary alloy over the entire loading range. The post-wear topographical surface features and chemical analysis using scanning electron microscope and energy-dispersive x-ray spectroscopy of the investigated alloys have suggested the oxidation and abrasion as dominant wear mechanisms. The reduced wear rates in the Al containing alloys are ascribed to the protective and continuous mechanically mixed oxide scale formation during test, which acts as a lubricating layer between the pin and the rotating disk. The discrete oxide island formation at the Zn-lean regions of Zn containing alloys is responsible for their accelerated wear rates. [ABSTRACT FROM AUTHOR]

The present study explores the preparation of Al–10wt.%Zn alloy by the casting process. Nano CuO was prepared by the Co-precipitation method. The effect of adding nanostructure of (1wt.% CuO) to Al–10Zn alloy was studied the corrosion effects as-cast and with different aging temperatures (423, 443, and 463 K) for 2 h in 3.5% NaCl aqueous solution after homogenized for 2 h at 500 K at room temperature. Electrochemical measurements (OCP, Tafel, and EIS) were performed to determine the corrosion rate (C.R.) and corrosion current density (Icorr.) to find out corrosion behavior. In addition, microstructures of Al–10Zn and Al–10Zn–1CuO were observed using a scanning electron microscope, EDX mapping, and the optical microscope to investigate the effect of the nanoparticle's addition before and after aging and the corrosion test. The average crystal size and the dislocation density were calculated from the XRD pattern. The results show that the appropriate addition of CuO nanoparticles can refine the Al–10Zn alloy and shift the Al–10Zn alloy to a more noble direction. [ABSTRACT FROM AUTHOR]

This study investigates and optimizes electro discharge face grinding (EDFG) for processing Monel 400 alloy. The EDFG process is complex, and choosing the appropriate input process parameters is challenging. In this work, the central composite design (CCD) of response surface methodology (RSM) was used to plan the experiments, and analysis of variance (ANOVA) was used to identify the significance of process parameters. This work aimed to assess the influence of grinding wheel speed (GWS) along with other process parameters on response parameters and to optimize the process parameters for the EDFG process. The ANOVA confirmed that GWS significantly affects the response parameters. Finally, the Desirability approach and Genetic algorithm (GA) optimizations were employed and compared to determine the best optimal process parameter settings for the process, with the three different objective function weights related to material removal rate (MRR) and average surface roughness (ASR). The optimum conditions were identified and confirmed through validation experiments. The machined surfaces were also analyzed using scanning electron microscope (SEM) images to assess the effects of the suggested parameter combinations. The study concluded that the GA approach was more effective in optimizing the EDFG process. [ABSTRACT FROM AUTHOR]

Zn has been added to the Al-12.5wt%Si-2wt%Cu-1wt%Mg (abbrev Al-12.5Si-2Cu-Mg) alloy. By utilizing optical microscope (OM), X-ray diffraction (XRD), and scanning electron microscope (SEM), the microstructure and phase structure of the alloy were investigated. The alloy's mechanical properties and wear resistance were evaluated. The results demonstrate that the as-cast microstructure of Al-12.5Si-xZn-2Cu-1Mg alloy consists of (α-Al + Si) eutectic, a minor amount of primary Si, θ-Al2Cu phase, Q-Al5Cu2Mg8Si6 phase, and π-Al8Mg3FeSi6 phase. In the final solidification zone of an alloy with a Zn content greater than 2%, a Zn-rich granular phase is observed. With an increase in Zn content, the size of the Si phase decreases and the number of θ-Al2Cu phase decreases. Zn slightly raises the formation temperature of primary Si, decreases the (α-Al + Si) eutectic transition temperature, and significantly decreases the formation temperatures of θ-Al2Cu and Q-Al5Cu2Mg8Si6 phases. The yield strength and hardness of the as-cast alloy raise with increasing Zn content, whereas the elongation decreases and the tensile strength first increases and then decreases slightly. The tensile strength is the greatest when the weight percentage of Zn is 2wt%. After T6 treatment, the tensile strength, yield strength, and hardness of the alloy rise in proportion to the alloy's Zn content, and its resistance to wear is greatly enhanced. [ABSTRACT FROM AUTHOR]

In this study, the effects of magnesium addition on the microstructure and comprehensive properties of Al-5Si-5.3Cu-0.3Sr-0.2Zr-0.2Y-0.06Ti alloys were investigated by optical microscope, scanning electron microscope, transmission electron microscope, hardness tester, and tensile testing machine. It is found that the addition of magnesium increases the number of undissolved particles in the alloy. However, on the one hand, magnesium addition refines the θ′ phase and increases its number density in the alloy. On the other hand, it generates a smaller Q′ phase. Both phases can enhance the precipitation strengthening and dislocation strengthening of the alloy. In addition, adding magnesium reduces the width of the precipitation-free zone (PFZ) and changes the distribution of grain boundary precipitates (GBPs). At 1% magnesium addition, the dislocation strengthening and precipitation strengthening effects of the θ′ and Q′ phases were the best, the width of PFZ was the smallest, and the GBPs were discontinuously arranged along the PFZ. Therefore, a high-strength, high-hardness, and intergranular corrosion-resistant cast aluminum alloy with dense structure, a tensile strength of 364.4 MPa, elongation of 4.87%, hardness of 145.4 HV, and intergranular corrosion grade of 3 was obtained. [ABSTRACT FROM AUTHOR]

This study investigated the hot workability of an experimental, non-toxic, low-cost Ti-3.4Fe alloy using flow stress analysis, constitutive modelling, processing maps and microstructural examination. Hot compression tests were performed on Ti-3.4Fe alloy samples at different deformation temperatures (750, 800, 850 and 900 °C), strain rates (0.05, 0.1, 1 and 10 s−1) and a total strain of 0.6. The compression tests were performed using a Gleeble® 3500 thermomechanical simulator. The isothermally compressed samples were analysed using a scanning electron microscope to assess the microstructure. An Arrhenius-based model was used to derive the constitutive constants. From the results, the stress exponent and activation energy were 4.91 and 611 kJ.mol−1 under the steady-state stress condition and 5.32 and 675 kJ.mol−1 at peak stress. The stress exponents suggested a dislocation climb and glide mechanism controlling deformation. The processing map showed that the optimum conditions to deform Ti-3.4Fe were 850 °C at a strain rate of 0.1 s−1 for both steady-state and peak stresses. The microstructure revealed kinked, rotated and bent lamella at the safe region (850 °C at 0.05 s−1), confirming the dominance of dynamic recovery as the softening mechanism. Instabilities manifested as cracks and inhomogeneity at 750 °C and 1 s−1 and at 850 °C and 10 s−1. [ABSTRACT FROM AUTHOR]

The microstructure and corrosion behavior of Ti-30Zr-xNb (x = 7, 10, 13 at.%) alloy for oil and gas downhole tools are studied. The microstructure of alloy is characterized by X-ray diffractometer (XRD), optical microscope (OM), and scanning electron microscope (SEM). The results show that with the increase of Nb content, the alloy changed from α″ phase and β phase to a single β phase, and the addition of Nb reduced the crystalline grain size. In addition, sub-grains are found in the original grains of TZN alloys, which may be due to the phase decomposition caused by the Nb content exceeding the solid solubility limit. The electrochemical behavior of the alloy is studied by measuring the open circuit potential (OCP), cyclic voltammetry curve (CV), Tafel curve (TF), and electrochemical impedance spectroscopy (EIS). Cyclic voltammetry curve and Tafel curve showed that the addition of Nb could stabilize the passivation film of Ti-Zr alloy and reduce the pitting sensitivity, among which Ti-30Zr-10Nb alloy has the best corrosion resistance, and its corrosion potential and current density are 0.36 (V) and 2.813 (× 10−8A cm2) respectively. EIS results show that Nb can significantly improve the corrosion resistance of the alloy by optimizing the microstructure of the passivation film. [ABSTRACT FROM AUTHOR]

Various electrochemical techniques were used to study the corrosion behaviour of the CNT-reinforced NiAl alloys under NaCl and Na2SO4 environments. The potentiodynamic polarization curves revealed activation Tafel behaviour when the NiAl alloy specimens were immersed in NaCl solution while passivation followed by slight development of transpassivation resulted under Na2SO4 environment. The reinforcement of pure NiAl alloy with up to 1.0 wt.% CNT increased the corrosion rate from 0.10 to 0.63 mm/yr under NaCl environment, while under Na2SO4 environment, the corrosion rate increased from 0.04 to 0.12 mm/yr. The observed increase in corrosion rate with an increase in CNT reinforcement (under both NaCl and Na2SO4 environments) suggested that the reinforcement of NiAl alloys with CNT reduced the corrosion resistance of NiAl. The X-ray diffraction analysis revealed that the corrosion products consisted of oxides including Al2O3 under NaCl environment, while scanning electron microscope analysis showed a porous passive layer on the surface of the alloy specimens immersed in Na2SO4 solution. [ABSTRACT FROM AUTHOR]

The effect of graphene nanosheets (GNPs) on the microstructure and corrosion resistance of ADC12 alloy in HCl solution were researched by optical microscope, scanning electron microscope, energy-dispersive spectrometer, x-ray diffraction and electrochemical measurements. The microstructural evolution revealed that the addition of GNPs could significantly refine the α-Al, Si and β-Al5FeSi phases, thus optimizing the microstructure of ADC12 alloy. The results of electrochemical experiments demonstrated that the corrosion current density of ADC12-0.9 wt.% GNPs alloy (1.18 mA cm−2) was 62.7% lower than that of the matrix (3.17 mA cm−2), and the corrosion potential (− 534 mV) was 8.4% higher than that of ADC12 (− 579 mV). Moreover, the value of polarization resistance (70.74 Ω cm2) was highest when adding 0.9 wt.% GNPs, indicating the improved corrosion resistance. The results of immersion tests indicated that the corrosion rate of the ADC12-0.9 wt.% GNPs alloy (VM = 16.31 ± 0.81 mg cm−2 d−1) was 62.3% lower than that of the matrix (VM = 43.16 ± 1.69 mg cm−2 d−1). Moreover, the effect of GNPs on the micro-galvanic corrosion for ADC12 alloy was discussed. [ABSTRACT FROM AUTHOR]

The oxidation behavior of Zr–2.5Nb alloy at 500 °C, 600 °C and 700 °C from 0.5 to 24 h in a tubular furnace with dry air was systematically investigated by scanning electron microscope, transmission electron microscope and nanoindentation techniques. The results indicate that there is an oxidation rate transition related to grain morphologies of the oxide layer. It showed that the equiaxed grains are good for the oxidation in pre-transition, while the columnar grains are unfavorable to the oxidation in post-transition. The oxide layers first grow with small equiaxed grains and then, become columnar grains. Both t-ZrO2 and m-ZrO2 were identified in the equiaxed grains, while only m-ZrO2 was identified in the columnar grains. Some sub-oxides with different morphologies were observed in the substrate at the beginning of oxidation and were not found after long time oxidation. The occurrence of the oxygen-assisted eutectoid phase transformation of βZr → αZr + βNb results in the decomposition of βZr phase and the precipitation of βNb phase in the microstructure near oxide layer/substrate interface. As the oxide layer thickens, its nano-hardness firstly increases and then decreases, while its adhesion increases gradually. The present study suggests that thicker oxide layers with limited microcracks may also be suitable for the bearing surface of artificial joints. [ABSTRACT FROM AUTHOR]

This work investigates the microstructure characterization and mechanical properties of Al alloy fabricated by additive friction stir deposition (AFSD). Microstructure characterizations of the Al alloy 5B70 base material (BM) and build were compared using optical microscope (OM) and electron back scattered diffraction (EBSD). The hardness distribution in the direction perpendicular to the cross-section of the deposited area was systematically evaluated. Tensile tests were performed on the BM and the build using digital image correlation (DIC), and the real-time stress distribution states of the specimens were analyzed. After the tensile tests, the fracture micromorphology was characterized using scanning electron microscope (SEM). The results indicated that a high degree of recrystallization occurred in the deposition zone, where fine, equiaxed, and differently oriented grains are formed. It was found that the strength of the deposition layer was lower compared to that of the BM, but its toughness was significantly improved. Also, obvious anisotropy of mechanical properties was identified in the deposition layer. [ABSTRACT FROM AUTHOR]

The hot deformation process significantly affects the performance of the manufactured Zr alloy components in nuclear reactors. The hot deformation behavior of the Zr-1wt.% Nb alloy with an initial β-quenched microstructure was evaluated using hot compression test at the temperature range of 600-950 °C and the strain rate range of 0.001-0.8 s−1. The constitutive equation was determined using kinetic analysis. The strong effect of Nb on decreasing self-diffusion in Zr was the reason for the obtained large activation energy of 390 kJ/mol in the Zr-1Nb alloy. Based on the dynamic material model, the processing map was constructed at the strain of 0.8 to show the stable and unstable hot deformation regions. The microstructural features of the hot deformed samples were observed using optical and scanning electron microscopes. The results indicated that the hot deformed microstructures were fully recrystallized so that the grain size of the as-received microstructure of the Zr-1Nb alloy was reduced from 1 mm to less than 4 μm after hot deformation at 800 °C. The optimum region in the hot deformation of the Zr-1Nb alloy with dynamic recrystallized microstructure and the peak efficiency of 40% was located at the temperature range of 675-775 °C and the strain rate range of 0.001-0.01 s−1. On the other hand, flow localization and macro-surface cracking occurred within the strain rate range of 0.1-0.8 s−1. [ABSTRACT FROM AUTHOR]

The effect of Ti content in various concentrations as an alloying element with Al on both microhardness and crystallization structure of aluminum–titanium alloys was studied, utilizing x-ray diffraction (XRD) and a scanning electron microscope (SEM). To study the electrochemical and corrosion performance of Al and its investigated alloys in 0.5 M solutions of HCl and H3PO4, two different techniques were used: extrapolation of Tafel plot and electrochemical impedance spectroscopy (EIS). Tafel plots and EIS revealed a similar trend. Generally, the rate of corrosion of the alloys was higher than that of Al. This investigation exhibited that the corrosion of Al alloying with Ti increased with an increase in both Ti content and temperature, which is due to reducing the growth of oxide film on the surface. Changes in the standard values of both entropy (ΔS) and enthalpy (ΔH), in addition to apparent activation energy (Ea) of corrosion processes of Al and its alloys in HCl and H3PO4, were evaluated. The evaluated data indicated negative values of ΔS, while the values of ΔH were positive. Besides, the decrease in ΔH value with the increase of Ti content in the alloy revealed that the dissolution of the studied alloys was fast. The positive values of ΔH were accompanied by an endothermic process. On the other hand, the activation energy (Ea) was decreased as a result of Al alloying with Ti in the two mentioned acids. Those results were supported by the corrosion current density (icorr.) and impedance parameters. By comparing the data obtained for both HCl and H3PO4 in all investigated electrodes, the corrosion current density (icorr.) in H3PO4 was lower than that in HCl. Such behavior can be ascribed to the aggressive attack of Cl¯ ions on the surfaces of the investigated electrodes, leading to pits formation. [ABSTRACT FROM AUTHOR]

Titanium and its alloys (especially Ti6Al4V) are widely employed in aerospace and biomedical industry. Wire electric discharge machining is common in practice to machine this difficult-to-cut material. But owing to the thermo-electric nature of the process, it is challenging to have adequate level of surface integrity. This primary concern needs to be addressed as it mainly influences the surface mechanical characteristics. Therefore, the present research aims to address the aforesaid issues using well-known multipass strategy. Understanding the multipass process dynamics and requirements, the potentiality of brass wire diameters was comprehensively examined and explored during WEDM of Ti6Al4V. Considering higher cost, unavailability, environmental hazards, and straightness issues of novel zinc-coated wire electrodes, readily available brass wires provide a cheaper and widely acceptable solution to enhance surface integrity of machined parts if equivalent results can be somehow made possible. For that sake, three different brass wire diameters; 0.15 mm, 0.2 mm, and 0.25 mm have been considered to evaluate their impact on surface roughness, recast layer thickness, overcut, machined surface microhardness, and cutting speed using multipass cutting technique. Experimental results revealed that 0.15 mm uncoated brass wire can produce white layer result equivalent to Topas Plus X wire (Cu core-double Zn-rich layer coating) which outperformed among all zinc-coated wires used in previously published research. Moreover, among different diameter brass wires, surface roughness is improved by 25% using multipass cutting with 0.15 mm diameter in comparison to its counterparts. Scanning electron microscope (SEM) analysis depicts that the said combination reduces recast layer thickness from 39.04 µm to 14.6 µm (~ 1.5 times lesser value). In addition to that, smaller diameter (0.15 mm) provides the maximum cutting rate in rough cuts (which consume maximum machining time) and dimensional accuracy. [ABSTRACT FROM AUTHOR]

In this research work, fabrication of Al alloy metal matrix composites (MMCs) reinforced with electroless Ni-P-coated Al2O3 is carried out using the stir-squeeze casting method. Scrap Al alloy wheels as matrix materials and Al2O3 particles as reinforcements are used to develop the MMCs. The Ni-P coating on Al2O3 particles is carried out using an electroless process to improve mechanical and tribological properties by increasing the bonding strength between the ceramic particles and the matrix material. A pre-treatment process on Al2O3 particles is done before the electroless Ni-P coating. To analyse the properties, the composites are fabricated in three different variations, i.e. as-cast scrap Al alloy, scrap Al alloy with uncoated Al2O3 (5 wt%), and scrap Al alloy with coated Al2O3 (5 wt%). Metallurgical properties are analysed using an optical microscope (OM), scanning electron microscope (SEM), energy-dispersive X-ray analysis (EDAX), and X-ray diffraction (XRD). The test results show that the porosity is reduced by 15.45% in a composite reinforced with coated Al2O3 compared to the as-cast scrap Al alloy. Also, the mechanical properties such as hardness, tensile strength, and impact strength are improved significantly by 15.2, 23, and 31.25%, respectively. Reduction of 31.47% in specific wear rate and 7.34% in coefficient of friction are achieved in the composite reinforced with coated Al2O3 particles compared to the as-cast scrap Al alloy. The compressive strength is decreased significantly with the addition of uncoated Al2O3 particles. After the addition of coated Al2O3, the compressive strength of the composite is increased compared with the uncoated Al2O3-reinforced composite. [ABSTRACT FROM AUTHOR]

Metallic powder alloys for additive manufacturing (AM) are required to have a certain particle size and shape distribution in different processes such as laser powder bed fusion for metallic alloys (LPBF-M). For reasons of sustainability and cost-effectiveness, it is common to recycle powder that was not melted in the build construction process. As usual in a LPBF-M process, the metal powder undergoes a heuristical designed sieving and blending procedure to maintain a certain particle distribution. However, keeping track of the powder's mean age during each building cycle can be obscure or laborious. To overcome this challenge, the authors of this research propose a theoretical model and an experimental methodology to track the powder morphology evolution with respect to a specific number of building cycles and the sieved and solidified amount of powder Such morphological investigation was carried out through a scanning electron microscope, analyzing the morphological evolution of nickel-chromium alloy metal (Inconel 718) powder. The powder analysis gives a close fit of its mean age to the span of the retained particle solidity measurements and the evolution of the mean major diameter. Recycling and thereby modifying the ageing rate of the powder, under monitoring the morphologic evolution of the particles, could be considered as a key criterion for a more effective powder usage lifetime. The findings from this methodology give insight on a predictive model for aging rate, capable of retrieving information about the effective powder's lifetime, impacting positively in the organization and storage of metal powders for AM. [ABSTRACT FROM AUTHOR]

Wear behavior of titanium alloys of Ti-4.5wt%Al + xFe (x: 2,4,6,8) produced by spark plasma sintering was investigated in order to highlight the effects of the iron additive on wear rate and coefficient of friction (COF). These research objectives were accomplished by a dry sliding experimental technique using the Tribometer (version 8.1.8) Anton Paar machine, which was carried out under normal loads at 10 N and 20 N with a linear speed of 0.06 cm/s. Scanning electron microscope (SEM) and X-ray diffraction (XRD) techniques were used to characterize the titanium alloy specimens. The results indicated that the wear rate increases with an increase in the applied normal load. A minimal coefficient of friction of 0.047 and a wear rate of 1.033 × 10−5 (mm3/N/M) were observed for Ti-4.5 wt% Al + 4 wt% Fe with respect to sliding at 10 N. While at a normal load of 20 N, a minimal friction coefficient of 0.015 and a wear rate of 1.74 × 10−5 (mm3/N/M) were obtained for Ti-4.5 wt% Al + 4 wt% Fe. [ABSTRACT FROM AUTHOR]

For the balanced consumption of pricey rare-earth element yttrium (Y) and improved pitting corrosion resistance of alloys, Y was partially substituted by cerium (Ce) in a novel kind of quinary AlNiCoYCex high-entropy metallic glass (HE-MG) via vacuum arc melting and rapid solidification. The microstructure, thermal stability and micro-hardness of Al30Ni30Co8Y32-xCex (x = 1, 2, 3, 4, 5, and 8 at%) high-entropy metallic glass ribbons (hereafter referred to as HE-MG ribbons) have been systematically investigated. In addition, the electrochemical corrosion properties of these amorphous ribbons with different Ce content in 3.5 wt.% NaCl solution have been determined by potentiodynamic polarization and electrochemical impedance spectroscopy. After 100 h immersion in corrosive media, scanning electron microscope images of the corroded ribbons were also characterized. The results indicated that these ribbon samples could remain in an amorphous state, and the that micro-hardness was more than 495 HV0.1. With increasing Ce content, the thermal stability started to gradually increase and then decrease. Furthermore, Ce is responsible for an improvement in anticorrosion performance compared with the Ce-free alloys. Ce-containing HE-MG ribbons showed a passive region in the electrochemical reaction, and ribbons with 3 at% Ce exhibited the most corrosion resistance by virtue of the smallest Icorr and Ipass. [ABSTRACT FROM AUTHOR]

The proton irradiation-induced hardening effect of dislocations in C35M FeCrAl alloy on glide resistance was quantified by in-situ micropillar compression testing in a scanning electron microscope (SEM). Irradiation tests with a proton energy of 2 MeV were conducted at room temperature, producing plateau damage of 0.01 and 0.1 displacement per atom (dpa), respectively, and generating high density of dislocation loops with fine size (<10 nm). Single-crystal micropillars were prepared with maximizing Schmid factor for a specific slip system while minimizing the others and then compressed to active one specific slip system to measure the critical resolve shear stress (CRSS) of {110}<111> and {112}<111> slip systems, respectively. The CRSS for these two slip systems increases with increasing irradiation dose. {112}<111> slip system shows larger hardening than {110}<111> slip system. Microstructure characterization after deformation indicates that the hardening effect originates from the pinning effect of irradiation-induced defects on moving dislocations. [ABSTRACT FROM AUTHOR]

Surface modification of dental implants or orthopedic implants is important for biocompatibility, and Ti-6Al-4 V alloy is mainly used as implant material for clinical use. In particular, research on the formation of nanotubes for drug doping to improve biocompatibility is in progress. For the control of nanotube shape, in this study, nanotube shape changes on Ti-6Al-4 V alloy via various applied potential for bio-implants were researched using various instruments. The formation of nanotubes on the surface of the Ti-6Al-4 V alloy was performed using a DC power source as a two-electrode system, and platinum as a counter electrode and a working electrode as an anode. The electrolyte was 0.8 wt. % NaF solution and 1.0 M H3PO4 were used and mixed using a magnetic bar during anodization. At this time, the voltage applied when forming the nanotubes was varied as (10 → 20 → 30 V), (30 → 10 → 30 V), and (10 → 30 → 30 V), respectively, and these voltages were applied for 30 min for each step. After the formation of nanotubes, the surface morphology and structural properties of the samples were observed using field-emission scanning electron microscope, X-ray diffractometer, Fourier transform infrared spectroscopy, and nanoindentation tester. The higher the voltage applied during the formation of nanotubes, the larger is the diameter. In the case of the nanotube (10 → 20 → 30 V), the top of the nanotube was narrow and the diameter increased toward the bottom, forming a cone shape. In the case of the nanotube (30 → 10 → 30 V), a narrow waist shape was formed, and in the case of the nanotube (10 → 30 → 30 V), a jar shape was formed with anatase and rutile phases. From the FT-IR results, when nanotubes are formed, TiO2 anatase was detected and showed the tendency to change from crystallization to amorphous state. The indentation hardness and elastic modulus decreased for the nanotube surface compared with those of the bulk Ti alloy. [ABSTRACT FROM AUTHOR]

The microstructure, tensile property and corrosion behavior of the die-casting AlSi10Cu3 alloy with 0.6 wt% (La + Yb) addition and T6 heat treatment are discussed. The results of optical microscope (OM) and scanning electron microscope (SEM) demonstrate the main phases are refined after the alloy is treated by two modification methods, and the distribution of Al2Cu phases becomes uniform after T6 heat treatment, thus increasing the ultimate tensile strength (UTS), yield strength (YS) and elongation by 21.6%, 31.4% and 52.5%, respectively. Simultaneously, the corrosion current density (iccor) reaches the minimum value of 5.89 mA·cm-2, which is reduced by 81.1%. Meanwhile, the hydrogen evolution rate and weight loss rate also reach the minimum value of 25.5 × 10-3 ml cm-2 h-1 and 116.5 μg·cm-2 h-1, and comparing with unmodified alloy, they are reduced by 54.6% and 52.2%, respectively. The optimized corrosion behavior is attributed to the refinement of the various cathode phases in the alloy. Moreover, parts of β-Al5FeSi phases are transformed into α-Al8Fe2Si phases and the uniform distribution of Al2Cu phases avoids severe local corrosion. [ABSTRACT FROM AUTHOR]

Grain refinement of Al–Si alloys is one of the effective methods for improving the elongation (El) and ultimate tensile strength (UTS). The influences of alone adding Ni (0.5, 1.0, 1.5, and 2.0%) and complex adding Ni (0.5, 1.0, 1.5, and 2.0%) plus 0.4%Y on the evolution of α-Al, eutectic Si, as well as mechanical performance of Al–7Si alloy, were investigated. All specimens were characterized by electron probe microanalysis, transmission electron microscopy, optical microscope, and scanning electron microscope. The results indicated that the secondary dendrite arm spacing (SDAS) of primary α-Al was markedly decreased with increasing Ni content in Al–7Si alloy. When the Ni addition concentration increased to 1.5%, the developed dendritic α-Al were effectively refined into fine equiaxed dendrites. Rare earth Y (0.4%) plus Ni were together added to Al–7Si alloys. The results showed that complex addition of Ni plus Y had a more outstanding refinement effect of α-Al and eutectic Si than that of Ni alone addition in Al–7Si alloy. The coarse and needlelike eutectic Si was modified into fine fibrous shape, and the SDAS of α-Al was significantly reduced when 1.5%Ni plus 0.4%Y was simultaneously added to Al–7Si alloy. Meanwhile, the mechanical performance test illustrated that the El and UTS were improved to 10.8% and 217.8 MPa, respectively. [ABSTRACT FROM AUTHOR]

In the present work, the effect of thermal cycles on the physical and thermal properties of AZ31 alloy and AZ31/5wt%SiC and AZ31/10wt%SiC composites was investigated. Samples were prepared using the stir casting method and then subjected to precipitation hardening. Thermal cycles were done for as-cast and aged samples with V-shaped notch under 300, 600, and 900 heating and cooling cycles at 150 and 350 °C. The crack length (CL) was evaluated using optical microscope (OM), scanning electron microscope (SEM), and energy-dispersive scanning electron (EDS) analysis. Also, density, porosity, thermal expansion coefficient of the samples were evaluated. X-ray diffraction (XRD) analysis was employed to assess the phases present in the material. The results demonstrated that by increasing the number of thermal cycles up to 600 at 150 °C and 350 °C, the porosity and density of the as-cast and aged AZ31 alloy decreased and increased, respectively; however, the density and open porosity were remained constant for the composite samples. The crack's length enlarged with increasing the thermal cycles from 300 to 600 µm at 150 °C and 300 to 900 µm at 350 °C. It was found that the reinforcement and precipitates prevented the rapid growth of the crack in the magnesium matrix. All in All, composite and the aged samples demonstrated better thermal fatigue resistance compared with that of the unreinforced alloy and as-cast samples, respectively. [ABSTRACT FROM AUTHOR]

As promising substitutes for Cu-Be alloys, Cu-Ni-Si series alloys have been investigated intensively concerning their mechanical and electrical properties but without much attention on their corrosion performance. Herein corrosion behaviors and mechanisms of the supersaturated and peak-aged CuNiSiCr alloys are investigated using salt spray test, x-ray diffraction, scanning and transmission electron microscopes. The corrosion rate of the aged sample is lower than that of the supersaturated one due to forming a denser protective corrosion product, Cu2O. Theoretical analyses indicate that the Cu2O film grows by oxidization of the matrix and its granular size is greatly influenced by the precipitates. The second corrosion product Cu2(OH)3Cl/CuCl2·3Cu(OH)2 forms by consuming the oxide Cu2O, which will induce pitting and deteriorate the corrosion resistance. Based on the obtained results, guidance concerning the composition and treatment optimization is provided for enhancing the anti-corrosion capability of the CuNiSiCr alloys. [ABSTRACT FROM AUTHOR]

A novel aluminum matrix composites (AMCs) reinforced by multiphase intermetallic compounds were fabricated through a conventional casting approach. The microstructure, compression properties and tribological behavior of the AMCs were detailed studied by the scanning electron microscope (SEM), x-ray diffraction (XRD), and electron probe microanalysis (EPMA). The results demonstrated that the fraction of precipitated multiphase intermetallic compounds gradually increased with the increase of high-entropy alloy (HEA) adding content, and the grain size of α-Al obviously was reduced. The irregular multiphase intermetallic compounds, such as Al70Cr20Ni10 and AlTiCrSi, are distributed in the Al matrix. However, the Al2Cu and Al7Cu4Ni distributed in inter-dendrites of α-Al. In addition, the compression strength of AMCs reinforced by 20.0 wt.% HEA addition was significantly enhanced to 530 MPa due to the precipitation of multiphase intermetallic compounds. Meanwhile, its compression strain was higher than 25%. Compared with pure Al, the microhardness of AMCs was extremely increased to 160 HV when the addition content of HEA was up to 20.0 wt.%. When the addition amount of HEA reached 10.0 wt.%, the COF of the ACMs was decreased by 51.6% from 0.766 to 0.371. When the HEA content was up to 20.0 wt.%, the wear rate reached the minimum of 4.87 × 10−5 mm3/N·m, which was reduced by 31.9% compared with pure Al. Furthermore, the strengthening effect and wear mechanism of AMCs reinforced by HEA addition was also discussed. [ABSTRACT FROM AUTHOR]

In general, Ti-6Al-4V alloys have been applied in recent metal cutting processes as an advantage of their immense strength concerning weight ratio at more corrosion resistance and temperature characteristics. It induces wide application in the automotive, nuclear, aerospace, biomedical, chemical, and naval industries. This recent research aims to establish the correlation between main input variables (cutting speed, axial feed rate, and depth of cut) and output characteristics (surface roughness, tool flank wear, and amplitude of vibration signal) in dry (no coolant) machining of Ti-6Al-4V alloy. The trials were conducted at variations of cutting speeds (75, 125, and 175 m/min), depth of cut (0.2, 0.4, 0.6 mm), and axial feed rate (0.1, 0.15, 0.2 mm/rev). The tool wear mechanisms were analyzed through scanning electron microscope. Also, the integrated multiple-output factors optimization method using a combined quality loss concept in the weighted principal component analysis coupled with the Taguchi analysis has been executed. With this, the optimal parameter setting has been found to be depth of cut (0.4 mm)–feed rate (0.1 mm/rev)–cutting speed (75 m/min). In this analysis, the optimized process input process variables determined will be definitely helpful to augment the performance characteristics of Ti-6Al-4V alloy in future research. [ABSTRACT FROM AUTHOR]

This work aimed to investigate the effects of some Bi additions (x = 0, 1, 3, and 5 wt%) added to Sn–2Cu solder alloy on its thermal properties, mechanical performance, and resistance to corrosion, which was investigated by using the Differential scanning calorimetry, Scanning electron microscope, Vickers Hardness Tester, Universal testing machine, Electrochemical workstation, and X-ray diffraction. The experimental results showed that doping 5 wt% Bi could reduce the melting point from 239.7 to 226.6 °C and the undercooling from 24.0 to 9.0 °C, which could improve the thermal properties. Moreover, the Bi addition could refine the microstructure and decrease the Cu6Sn5 IMC phases' size. With the addition of 5 wt% Bi, the microhardness and tensile strength reached the highest value of 20.13 HV and 57.64 MPa, respectively, due to the solid solution strengthening and precipitation strengthening. The electrochemical corrosion behaviors were performed to use the potentiodynamic polarization and electrochemical impedance spectroscopy. The obtained results revealed that a dense passivation film was formed on the surface of Sn–2Cu–1Bi alloy to prevent the alloy from being further corroded, which had the lowest value of corrosion current density (0.034 μA·cm−2) and biggest value of total resistance (200.4 kΩ·cm2). Therefore, the Sn–2Cu–1Bi alloy had best corrosion resistance. [ABSTRACT FROM AUTHOR]

The effects of Ag content and hot-rolling on the microstructure and mechanical properties of Zn-1.5Cu-xAg-0.1Zr(x = 0, 0.1, 0.5, 1.0) alloys were investigated. The microstructure, phase composition and fracture morphology of the alloys were observed and analyzed by optical microscope, x-ray diffraction, scanning electron microscope, energy dispersive spectrometer and universal mechanical testing machine. The results show that Ag has the effect of grain refinement. After alloying, the grain size of as-cast Zn-1.5Cu-xAg-0.1Zr alloy decreased first and then increased, and the minimum grain size of as-cast Zn-1.5Cu-0.5Ag-0.1Zr alloy was refined to 64.18 μm. At the same time, new phase AgZn3 began to precipitate, the yield strength (YS), ultimate tensile strength (UTS), and elongation (EL) of alloys were also up to 97.35 MPa, 139.25 MPa and 7.60%, respectively. After hot-rolling, the grain of Zn-1.5Cu-xAg-0.1Zr alloy was broken and new phase CuZn5 was precipitated. The mechanical properties were significantly improved, and the maximum YS, UTS and EL of as-rolled Zn-1.5Cu-1.0Ag-0.1Zr alloy were 218.14MPa, 244.83MPa, 64.50%, respectively. [ABSTRACT FROM AUTHOR]

Nimonic alloy 75, a high strength temperature resistant material, has widespread applications in gas turbine engines, industrial furnaces, nuclear engineering, etc. This paper presents a comparative study of capabilities evaluation between the conventional electrical discharge machining (EDM) and ultrasonic-assisted-electrical discharge machining (UAEDM) of Nimonic alloy 75 work material. During experimentation, input parameters namely tool material; discharge current; servo voltage and pulse on duration were varied to find their effects on material removal rate (MRR) and surface roughness (SR). Results indicated that UAEDM process leads to an increase of 53.57% in MRR over conventional EDM process, whereas SR of UAEDM process is 18.47% higher compared to conventional EDM process. Scanning electron microscope 'SEM' images shows that UAEDM process has fewer surface irregularities compared to conventional EDM process. Energy-dispersive x-ray (EDS) test has shown tool material migration and carbon enrichment of EDMed and UAEDMed surfaces. X-ray diffraction 'XRD' analysis has shown the formation of NiC phase on EDMed and UAEDMed surface when compared to unmachined surface. Further, a significant reduction in crystallite size was observed for EDMed and UAEDMed surface in comparison to unmachined surface. The surface microhardness increased after conventional EDM and UAEDM process as compared to unmachined surface. [ABSTRACT FROM AUTHOR]

The development of magnesium alloys with superior plasticity and favorable strength is still challenging in aerospace industry. Herein, hot extruded Mg-xNd-2.0Sm-0.4Zn-0.4Zr alloys (x = 0, 0.5, 1.0, 1.5, 2.0 and 2.5 wt.%) were rationally designed and easily prepared in order to implement the favorable combination of strength and plasticity. The effects of Nd element addition on the microstructure and mechanical properties of the hot extruded alloys were systematically investigated by optical microscopy (OM), scanning electron microscope (SEM) and transmission electron microscopy (TEM). The OM results indicated that the grain size of the hot extruded alloys decreased from 27.1 to 14.1 μm with increasing Nd addition from 0 to 2.5 wt.%. Some coarse β phases existed at the grain boundary when the addition of Nd element increased to 2.0 wt.%. The TEM results showed that the nanoscaled basal lamellar precipitates, granular precipitates and prismatic lamellar precipitates formed in α-Mg matrix. And the amount of precipitated phase increased obviously with the increase of Nd element addition. The ultimate tensile strength increased significantly from 203 ± 3.0 to 237 ± 2.5 MPa, and the elongation decreased from 30.5 to 21.2 % when the Nd elements increased from 0 to 2.5 wt.%. The fractographs of the hot extruded alloys could be classified as ductile fracture. [ABSTRACT FROM AUTHOR]

The corrosion behavior and microstructure of Mg-3Zn-1Mn-xSr (x = 0, 0.5, 1.0, 1.5, 2.0 wt.%) alloys are investigated by optical microscope (OM), scanning electron microscope (SEM), electrochemical tests and immersion experiments equipped with a dynamic corrosion device. The introduction of Sr element changes the distribution of Mg7Zn3 phase in the Mg-3Zn-1Mn alloy, promoting its precipitation at the grain boundary. Decrease in grain size and second phase spacing can be observed with the increase of Sr content, and the size of semi-continuous second phases (Mg7Zn3 + Mg17Sr2) distributed along grain boundary increases. The corrosion resistance of Mg-3Zn-1Mn-xSr alloys increases with the suitable addition of Sr, but decreases with the addition of excessive Sr, indicating that the critical value exists for the addition of Sr to obtain the optimal corrosion resistance. Optimal corrosion performance (CR = 1.213 ± 0.02mm/y, Icorr = 2.80μA/cm2) of Mg-3Zn-1Mn-1Sr alloy is concluded by immersion tests and electrochemical measurements, and its corrosion morphology manifests uniform corrosion pits and dense structure due to mass accumulation of corrosion products on the damaged surface of Mg matrix. The synergistic effect of the grain size and second phase is used to explain the influence of the variation of Sr content on the corrosion performance of Mg-3Zn-1Mn-xSr alloys. [ABSTRACT FROM AUTHOR]

Hydroxyapatite-carbon nanotubes (HA-CNTs) nanocomposite coating was applied by electrophoretic method on anodized Ti alloy to investigate its stability in simulated body fluid (SBF). The biocoating was characterized by using scanning electron microscope (SEM) for microstructure, X-ray diffraction (XRD) for crystallography. The effect of CNTs concentration on the coating properties was also investigated and found out that CNTs up to 5% has various improving effect on the system. It increased corrosion resistance and adhesion of the coating to the substrate and decreased the number of cracks on the coating. The results of the in vitro test showed that the cell viability increased with increasing the concentration of CNTs to 3 wt.% CNTs. [ABSTRACT FROM AUTHOR]

The effect of scandium content on the structure and properties of alloy Al – 4.5% Zn – 4.5% Mg – 1% Cu – 0.12% Zr is determined. The microstructure of the alloy is studied with identification of the phases using an optical microscope and scanning and transmission electron microscopes. The Vickers hardness and the yield strength under heating are determined. The phase diagram is plotted and the nonequilibrium crystallization is described using the Thermo-Calc software and the TTAL5 database. It is shown that addition of 0.1% scandium contributes substantially enough into the growth of the hardness after 3-h annealing at 450°C and into the yield strength after 20-h aging at 175°C. The compositions studied are recommended as a base for designing new refractory alloys based on the Al – Zn – Mg – Cu system. [ABSTRACT FROM AUTHOR]

In this work, static mass analysis method and electrochemical test experiment were used to study the corrosion resistance of Mg-12Gd-3Y-1Sm-0.8Al alloy in different heat treatment states. Optical microscope, scanning electron microscope and x-ray diffractometer were used to analyze microstructure. The result shows: The microstructure of different samples are composed of α-Mg, Mg5Gd, Mg24Y5, Mg41Sm5 and Al2RE phases. Heat treatment can change the morphology and distribution of the precipitates, and the precipitates can affect the corrosion behavior as a cathode, thereby improving the corrosion resistance of the alloy in 3.5% NaCl solution. The relative corrosion rates of the different samples can be ranked as T6>T6-18h>T4>As-cast. After aging treatment, the fine and continuous precipitates act as a barrier to prevent the propagation of corrosion. At this time, the alloy has the strongest corrosion resistance. [ABSTRACT FROM AUTHOR]

In this study, a new alloy material Mg-Zn-Zr (ZK60) was designed for the connecting rod. It was found that the blanks sampled along the vertical direction of an extruded bar crack during the roll forging process. The microstructure and precipitates of the extruded bar were observed and analyzed using optical microscope (OM), scanning electron microscope (SEM) and x-ray diffraction (XRD). The result showed that the Zn, Zr, and MnZn2 precipitates were elongated along the extrusion direction. The mechanical anisotropy was investigated by testing the mechanical properties of the specimens sampling from different angles. Hot deformation behavior was further studied using the Gleeble 3500 thermal-mechanical simulator. The tensile and yield strengths were the highest along the extrusion direction, reaching 347 MPa and 301 MPa, respectively. The deformation resistance was also higher in the extrusion direction than that in the vertical direction. Fracture mechanisms of the sample from different directions were discussed. The ZK60 alloy was more susceptible to failure if the deformation direction was parallel to the bands of segregation area and precipitates. [ABSTRACT FROM AUTHOR]

A novel biomaterial Ti-17Mo (mass%) was designed for orthopedic implant applications. Hot working behavior and deformation characteristics were studied in the β-single structure by hot compression tests in the strain rate range 0.01–10 s−1 and temperature range 1123–1273 K using a Thermec Master-Z simulator. The microstructural evolutions of the deformed alloy were studied by a scanning electron microscope equipped with an electron backscattered diffraction detector. The microstructures of the hot deformed alloy showed that dynamic recovery was more active than dynamic recrystallization (DRX). However, partial discontinuous DRX by grain boundary bulging is activated at high temperatures and low strain rates, e.g., 1273 K and 0.01 s−1. Due to the high stacking fault energy of the β phase with a bcc structure, the Ti-17Mo alloy possessed comparatively low activation energy of hot deformation (283 kJ/mol) compared with the conventional Ti alloys bearing multiple alloying elements. [ABSTRACT FROM AUTHOR]

In this study, Mg-xAl-3Zn alloys (x=0.5-1-2-3 wt.%) were produced by the permanent mold casting method. Microstructural characterization of alloys was done with the help of optical microscope (OM) and scanning electron microscope with energy-dispersive spectroscopy (SEM/EDS). Dry and bio-corrosive wear behaviors of alloys were investigated comparatively. Depending on the amount of Al in the alloys, the intermetallic phases were differentiated. Mg17Al12 phase was only observed in Mg-3Al-3Zn alloy distributed along the grain boundary as a continuous or semicontinuous network. The Mg-3Al-3Zn alloy hardness value was about 61.60±4.23 HV and approximately 30% higher than the other alloys. Dry wear and bio-corrosive (in simulated body fluid (SBF)) wear performances of the alloys were also compared. The abrasive wear mechanism was evident in dry ambient wear due to the intermetallic phases in the structure. Still, the liquid's lubrication effect is much more dominant in the bio-corrosive wear tests carried out in SBF. While Mg-3Al-3Zn wear rate was the lowest in dry wear, it was determined to be the highest in bio-corrosive wear for all applied load conditions. It had been understood that a large amount of Mg17Al12 phase in the structure caused such a result. [ABSTRACT FROM AUTHOR]

The beryllium bronze guide sleeve and the aluminum alloy valve body are assembled to form a beryllium bronze-aluminum alloy stepped hole which requires multiple positioning and tool changes during machining, resulting in lower machining efficiency and accuracy. The geometry error and surface quality of beryllium bronze-aluminum alloy stepped holes after reaming were studied in this research. The geometric error (cylindricity, concentricity and verticality) and diameters of the stepped holes were measured by using a three-coordinate measuring machine. The experimental results show that the PCD forming cutters has high geometric error and diameter stability when reaming beryllium bronze-aluminum alloy stepped holes. Under various cutting parameters, the cylindricity of stepped holes was guaranteed to be within 6μm, and the concentricity of stepped holes was guaranteed to be within 6μm, and verticality of stepped holes was guaranteed to be within 2μm. With the increase of spindle speed and feed per tooth, the diameters of beryllium bronze holes increase while the diameters of aluminum alloy holes decrease and then increase. As the cutting allowance increases, the diameters of the beryllium bronze holes and aluminum alloy holes decrease. The laser confocal microscope and scanning electron microscope were used to detect and analyze the surface quality of beryllium bronze-aluminum alloy stepped holes after reaming. The experimental results show that the surface roughness of the beryllium bronze-aluminum alloy stepped holes reamed by using the PCD forming cutter were less than 0.3μm, and the surface roughness of the beryllium holes were slightly larger than the aluminum holes. The fourth group of experimental parameters (spindle speed 1290r/min, feed per tooth 0.01mm/z, cutting allowance 0.06mm) was selected as the actual processing parameters. There are cavities on the surface of the initial stepped holes before reaming and the cavities basically disappear after reaming, so the surface quality of the beryllium bronze-aluminum alloy stepped holes has been greatly improved. [ABSTRACT FROM AUTHOR]

Applications at elevated temperature require alloys that can form a protective oxide layer, and Cr and Si are known to form these layers, allowing FeCrSi alloys to be oxidation resistant. However, few studies have considered Si content higher than 2 wt.%. The objective here was to analyze the cyclic oxidation resistance of innovative FeSiCrNi alloys with different Si and Cr contents (around 5 wt.% of both). Cyclic oxidation tests were performed on three alloys at 950 °C in still air. The microstructure of the cast and heat-treated alloys and the oxide scales formed were analyzed by scanning electron microscope and energy-dispersive X-ray spectroscopy. Oxide layers were also characterized by X-ray diffraction. Comparing silicon contents of 4.65 and 5.9 wt.% in two different alloys containing around 4 wt.% chromium and 0.8 wt.% carbon, it was demonstrated that the lower silicon content was not enough to avoid iron oxides formation and continuous spallation. On the other hand, the higher silicon alloy exhibited low mass gains and a protective oxide layer composed of Cr2O3 and MnCr2O4, with some enrichment of silicon at metal/oxide interface. A third alloy, containing 2.7 wt.% carbon and, thus, graphite in its microstructure suffered decarburization in some regions, although in other regions it formed a protective oxide even in an alloy containing 3.25 wt% Cr and 6.6 wt.% Si. These results demonstrate that it is possible to have a high-temperature resistant alloy with low Cr content relative to conventional alloys by using high Si additions. [ABSTRACT FROM AUTHOR]

Streams of multimodal three-dimensional (3D) and four-dimensional (4D) data are revolutionizing our ability to design and predict the behavior of a broad array of advanced materials systems. Over the last 10 years, a new 3D imaging platform consisting of a femtosecond (fs) pulsed laser coupled with a focused ion beam scanning electron microscope (FIB SEM) has been developed by UC Santa Barbara in collaboration with Thermo Fisher Scientific (formerly FEI). The femtosecond-laser-enabled FIB SEM, called the TriBeam, has become one of the only 3D serial sectioning methods available that can gather millimeter-scaled multimodal datasets at sub- μ m voxel resolutions; these length scales are critical for many materials problems. Multimodal chemical, crystallographic, and morphological information can be gathered rapidly on a layer-by-layer basis and reconstructed in 3D. Large (gigabyte to terabyte scale) 3D datasets have been generated for a broad array of materials systems, including metallic alloys, ceramics, biomaterials, polymer- and ceramic-matrix composites, and semiconductors. The research tasks performed have resulted in a completely new design, operating with a dual-wavelength femtosecond-pulsed laser on a plasma focused ion beam (PFIB) platform. [ABSTRACT FROM AUTHOR]

Thermite reduction as one of the most promising methods for preparation of TiAl alloy, the metal-slag separation behavior in the whole process of chemical reaction, including both the alloy components and slags to be removed, is still ambiguous. In this paper, the two-step nucleation mechanism was applied to investigate the metal-slag separation behavior in the thermite reduction process for the preparation of TiAl alloy, which was confirmed by thermodynamic calculation based on density functional theory. Moreover, the component of products acquired from thermite reaction was characterized and analyzed by x-ray diffractometer, scanning electron microscope and transmission electron microscope, respectively. According to the results of the experiment and calculation, the formation and separation mechanism between alloy and slag in the process of preparing TiAl alloy via thermite reduction is visualized, which is universal in the whole metallurgical procedure involving redox and slag-making process. [ABSTRACT FROM AUTHOR]

Influence of Equal Channel Angular Pressing on mechanical properties and fracture toughness of Al-Zn alloy were studied in present investigation. Samples are successfully processed using the ECAP technique for up to a four passes by using route A. Al-Zn alloys were heated to a solid solution treatment temperature at 550 °C for 2 h prior to ECAP, this treatment introduces the precipitates which were capable of obstructing motions of dislocation and improves the refinement of the grain during ECAP process Finally, artificial aging was performed at a temperature of 190 °C for 0-20 hours with an interval of 2 h and specimens were cooled at room temperature with natural air. Fracture toughness was found experimentally for ECAP processed samples using SE (B) specimens according to ASTM E399 standard. This study revealed the enhancement in mechanical properties such as yield strength, ultimate strength and microhardness after four passes by route A technique. The improvement in the fracture toughness properties of artificially aged ECAP samples can also be due to dislocation strengthening, grain boundary strengthening, and the creation of much finer UFG grains, according to the results. Despite the increased tensile strength after ECAP, the ductility behavior has decreased due to the precipitation of GP zones and dispersion of η, ή, T and E within the Aluminum matrix, Furthermore, scanning electron microscope (SEM) micrographs revealed that ductile fracture with large dimples occurred in the artificial aged samples after the ECAP procedure. [ABSTRACT FROM AUTHOR]

In this study, the machining characteristics of pulse short arc milling (SEAM) Ti6Al4V alloy were studied. In this regard, the influence of SEAM parameters on the material removal rate (MRR), relative electrode wear ratio (REWR), and surface integrity of Ti6Al4V is studied. A wide variety of processing parameters, including different voltages, frequencies, duty cycles, flushing pressures, electrode rotation speeds, and electrode feed rates, are considered in the investigation. Scanning electron microscope (SEM), energy dispersive spectrograph (EDS), and micro-hardness analysis are applied to analyze results. Moreover, a multichannel data acquisition system is used to measure gap voltage and gap current. Obtained results cover the variation of MRR, REWR, surface roughness (Ra), average resolidified layer thickness, and average heat-affected zone thickness with different processing parameters. Furthermore, the electrode surface morphology and chemical composition of the negative growth of REWR are studied. Based on the obtained results, the microstructure of the resolidified layer and heat-affected zone of the workpiece cross-section is confirmed. This study provides a basis for the high-quality pulse SEAM technology of difficult-to-machine (DTM) materials to enter the semi-finishing field. [ABSTRACT FROM AUTHOR]