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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]

To perform quality assessments of both metal alloys and many other engineering materials, measurements of the volume fractions of phases or microstructure components are utilized. For this purpose, quantitative analysis of the evaluated components' distribution on metallographic specimens is often employed. Phases or components of the microstructure are identified based on the variation in signal received in the band of light seen. Problems with the correct identification of measurement results in this spectral band can be caused by the inhomogeneity of the etching when the alloy components are segregated. Additional uncertainty arises when the analyzed image pixel contains a boundary between grains of different phases. This article attempts to use the results of local chemical composition measurements as a source signal for quantitative evaluation of phase composition. For this purpose, quantitative maps of elemental concentration distributions, obtained with a Tescan Mira GMU high-resolution scanning electron microscope in QuantMap mode, were used as input data for the phase composition evaluation of an EN AC 46000 alloy sample. The X-ray microanalysis signal generation area may contain grains of more than one phase. Therefore, evaluation of the phase fractions in areas of individual measurements were calculated by looking for the minimum of the objective function, calculated as the sum of the squares of the deviations of the results of measurements of the concentration of individual elements from the weighted average values of solubilities of these elements in the phases. [ABSTRACT FROM AUTHOR]

The FurnaSEM microfurnace was installed in the chamber of a scanning electron microscope to carry out in situ experiments at high temperatures and test its limits. The microfurnace was used in combination with different types of detectors (Everhart–Thornley for the collection of secondary electrons in a high vacuum, gas secondary electron detector for the specific collection of secondary electrons in the presence of gas, and Karmen© detector for the collection of backscattered electrons at high temperature). Experiments carried out on various samples (metal alloys and ceramics) show that the microfurnace operates in both high-vacuum and low-vacuum modes. Temperature ramp rates during temperature cycles applied to the sample range from 1 to 120 °C/min (temperature rise) and 1 to 480 °C/min (controlled and natural cooling). The maximum temperature at which images were recorded up to 25 k × magnification was 1340 °C, with a residual air atmosphere of 120 Pa. The choice of a flat furnace with the sample placed directly above it has enabled innovative experiments to be carried out, such as low-voltage imaging (using a shorter working distance—up to 10 mm—than is possible with conventional furnaces), 3D imaging (by tilting the stage by up to 10°), and high-temperature backscattered electron imaging (using a dedicated detector). [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]

Due to the poor activation performance and kinetics of Ti50V25Cr25 alloys, the element Zr was added to improve the phase structure of the alloy and achieve a high-performance hydrogen storage alloy. The Ti50−xV25Cr25Zrx (x = 0, 5, 7, and 9) system alloys were prepared by arc melting. The alloys were analyzed using an X-ray diffractometer (XRD), scanning electron microscope (SEM), and differential scanning calorimeter (DSC). The hydrogen storage capabilities of the alloys were also obtained by the Sievert volumetric method. The results indicated that the alloy with Zr added had a combination of the C15 Laves phase and the BCC phase, whereas the Zr-free alloy had a BCC single phase. The partial replacement of Zr with Ti resulted in an increase in the lattice parameters of the main phase. The hydrogen storage kinetic performance and activation of the alloys both significantly improved with an increasing Zr concentration. The time to reach 90% of the maximum hydrogen storage capacity decreased to 2946 s, 230 s, and 120 s, respectively, with the increases in Zr concentration. The initial hydrogen absorption content of the alloys increased and then decreased after the addition of the element Zr. The second phase expanded with an increasing Zr concentration, which in turn decreased the abundance of the BCC main phase. The Ti43V25Cr25Zr7 alloy showed good cycle stability and hydrogen-desorption performance, and it could absorb 90% of the maximum hydrogen storage capacity in around 230 s. The maximum hydrogen-absorption capacity of the alloy was 2.7 wt%. The diffusion activation energy of hydrogen desorption dropped from 102.67 kJ/mol to 92.62 kJ/mol. [ABSTRACT FROM AUTHOR]

The anisotropic damage behavior has a great influence on the formability of rolling sheets. This work aimed to investigate the anisotropic damage mechanism of the LA103Z Mg‐Li alloy rolling sheet by combining mesoscale detection and modeling. The X‐ray computed tomography (XCT) and scanning electron microscope (SEM) were applied to characterize the evolution of damage morphology and volume fraction in RD, DD, and TD directions of the rolling sheet. The GTN damage model was calibrated by the experimental results with the representative volume element (RVE) method. The anisotropic damage mechanism was revealed via experimental and modeling results. The micro void nucleation strain εN was critical to determine the initiation moment of the anisotropic damage. The continuous nucleation in RD direction, the severe growth in DD direction, and the massive coalescence in TD direction were the micro void evolution competition results that caused the anisotropy for damage mechanism and fracture strain. Highlights: The micro void evolution was quantitatively characterized by XCT and SEM methods.The GTN damage model calibrated by the RVE method exhibited accurate prediction.εN was the critical strain for determining the initiation of anisotropic damage.Anisotropic damage was caused by different responses of micro void evolution. [ABSTRACT FROM AUTHOR]

The deformation aspects associated with the micro-mechanical properties of the powder laser bed fusion (P-LBF) additively manufactured stainless steel 316L were investigated in the present work. Toward that, micro-pillars were fabricated on different planes of the stainless steel 316L specimen with respect to build direction, and an in situ compression was carried out inside the chamber of the scanning electron microscope (SEM). The results were compared against the compositionally similar stainless steel 316L, which was fabricated by a conventional method, that is, casting. The post-deformed micro-pillars on the both materials were examined by electron microscopy. The P-LBF processed steel exhibits equiaxed as well as elongated grains of different orientation with the characteristics of the melt-pool type arrangements. In contrast, the cast alloy shows typical circular-type grains in the presence of micro-twins. The yield stress and ultimate compressive stress of P-LBF fabricated steel were about 431.02 ± 15.51 − 474.44 ± 23.49 MPa and 547.78 ± 29.58 − 682.59 ± 21.59 MPa, respectively. Whereas for the cast alloy, it was about 322.38 ± 19.78 MPa and 477.11 ± 25.31 MPa, respectively. Thus, the outcome of this study signifies that the AM-processed samples possess higher mechanical properties than conventionally processed alloy of similar composition. Irrespective of the processing method, both specimens exhibit ductile-type deformation, which is typical for metallic alloys. [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]

Purpose: FeNi36 (Invar-36) alloy is widely used in the fabrication of molding tools in aerospace industries but there remains a need to improve its wear and friction performance due to its relatively low hardness. The formation of a heat affected zone (HAZ) on the surface of Invar-36 cut by wire electric discharge machining (WEDM) is promising to enhance its tribological properties. This study aims to investigate the tribological performance of WEDM-treated Invar-36 via a ball-on-disk tribometer in dry-sliding conditions. Design/methodology/approach: The untreated and WEDM-treated Invar-36 surfaces were reciprocated against an alumina ball at a sliding velocity of 40 mm/s, a stroke length of 10 mm and a sliding duration of 125 min under loads of 5, 10 and 20 N. The worn surfaces were characterized using a 2D profilometry and a scanning electron microscope equipped with energy-dispersive spectroscopy. Findings: The results showed that the WEDM-treated surface had a superior friction coefficient and wear resistance in comparison to the untreated surface, due to the grown HAZ. There was found to be a 9.3%–11.4% decrease in the friction coefficient and a 47%–57% reduction in the wear volume after the WEDM treatment. Both the untreated and WEDM-treated Invar-36 surfaces found abrasion and plastic deformation as the dominant wear mechanisms. Originality/value: Previous works have not focused on the tribological performance of the WEDM-treated Invar-36 extensively used for molding tools in aerospace industries. Our findings provide compelling evidence that the WEDM treatment improved the wear and friction performance of Invar-36 alloy because of the grown HAZ. [ABSTRACT FROM AUTHOR]

The microstructure and properties of an AlSi10Mg alloy produced by selective laser melting were examined using optical microscopes, scanning electron microscopes, electron backscattered diffraction, and x‐ray diffraction. The results show that the mechanical characteristics of selective laser melting formed AlSi10Mg alloy is superior to those of traditional sand cast AlSi10Mg alloy due to fine grain strengthening and solid solution strengthening. AlSi10Mg alloy formed by selective laser melting is mainly composed of α‐aluminum solid solution, eutectic silicon with network structure and a small amount of Magnesium silicon precipitated phase, and different cross‐sections have unique microstructures and properties. The XOY plane is composed primarily of equiaxed grains with an average grain size of 7.34 μm and a {001} <100> cubic texture, and it has a hardness value of 130.7 HV 0.2. The majority of the YOZ plane, which has a {111}<110> brass R texture and a hardness value of 108.9 HV 0.2, comprises columnar crystals with an average grain size of 8.42 μm. [ABSTRACT FROM AUTHOR]

Hot-dip aluminum alloy is widely used in the engineering fields. However, during the aluminum plating process, Fe inevitably enters and reaches a saturation state, which has a significant impact on the corrosion resistance and microstructure of the coating. Currently, adding Si during the hot-dip aluminum process can effectively improve the quality of the coating and inhibit the Fe-Al reaction. To understand the effect of Si content on the microstructure and electrochemical performance of Al-xSi-3.5Fe coating alloys, the microstructure and post-corrosion morphology of the alloys were analyzed using SEM (Scanning Electron Microscope) and XRD (X-ray Diffraction). Through electrochemical tests and complete immersion corrosion experiments, the corrosion resistance of the coating alloys in 3.5 wt.% NaCl was tested and analyzed. The results show that the Al-3.5Fe coating alloy mainly comprises α-Al, Al3Fe, and Al6Fe. With the increase in Si addition, the iron-rich phase changes from Al3Fe and Al6Fe to Al8Fe2Si. When the Si content reaches 4 wt.%, the iron-rich phase is Al9Fe2Si2, and the excess Si forms the eutectic Si phase with the aluminum matrix. Through SKPFM (Scanning Kelvin Probe Force Microscopy) testing, it was determined that the electrode potentials of the alloy phases Al3Fe, Al6Fe, Al8Fe2Si, Al9Fe2Si2, and eutectic Si phase were higher than that of α-Al, acting as cathode phases to the micro-galvanic cell with the aluminum matrix, and the corrosion form of alloys was mainly galvanic corrosion. With the addition of silicon, the electrode potential of the alloy increased first and then decreased, and the corrosion resistance results were synchronous with it. When the Si content is 10 wt.%, the alloy has the lowest electrode potential and the highest electrochemical activity. [ABSTRACT FROM AUTHOR]

The low strength caused by the single FCC structure of the CrMnFeCoNi high entropy alloy (HEA) limits its application in the field of coating. Here, we prepared high-entropy alloy coatings of CrMnFeCoNi with different ZrC contents on Q235 steel by a plasma transferred arc process. The effects of ZrC on the microstructure and properties of the CrMnFeCoNi HEA coating were investigated by optical microscopy, scanning electron microscope, and X-ray diffraction and by employing a potensiostat/galvanostat. The results showed that ZrC mainly existed in the coatings as a second phase, having little influence on the main crystal structure and micromorphology of the CrMnFeCoNi HEA coating. The hardness of the CrMnFeCoNi HEA coating increased with the ZrC content. ZrC can effectively improve the corrosion resistance of the CrMnFeCoNi HEA coating. In a 1 mol/L NaCl solution with 4 wt% ZrC, the annual corrosion rate was only 5.997% of that of the HEA coating. Nevertheless, the improvement in the wear resistance of CrMnFeCoNi high-entropy alloy coatings was not apparent with the addition of ZrC. Consequently, the addition of ZrC to the FeCoCrNiMn high-entropy alloy coating holds promise for applications in corrosion resistance, particularly in oceanic environments. [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]

Purpose: The purpose of this study is to describe the mechanism of single-crystal high-temperature creep deformation, predict the creep life more accurately and study the creep constitutive and lifetime models with microstructure evolution. Design/methodology/approach: The mechanical properties of nickel-based single-crystal superalloy are closely related to the γ' phase. Creep tests under four different temperature and stress conditions were carried out. The relationship between creep temperature, stress and life is fitted by numerical method, and the creep activation energy is obtained. The creep fracture surface, morphology and evolution of strengthening phase (γ') and matrix phase (γ) during different creep periods were observed by scanning electron microscope. With the increase of creep temperature, the rafting time is advanced. The detailed morphology and evolution of dislocations were observed by transmission electron microscope (TEM). Findings: With the increase of creep temperature, the rafting time is advanced. The detailed morphology and evolution of dislocations were observed by TEM. Dislocations are mainly concentrated in the γ channel phase, especially at high temperature and low stress. Originality/value: A creep constitutive model based on the evolution of γ' phase size and γ channel width was proposed. Compared with the experimental results, the predicted creep life is within 1.4 times error dispersion band. [ABSTRACT FROM AUTHOR]

Ti films with different thicknesses were successfully deposited on the surface of WE43 alloy by filtered cathode vacuum arc technology, and the microscopic morphology, structural composition, and corrosion resistance of the films were studied by means of X‐ray diffractometer, X‐ray photoelectron spectroscopy and scanning electron microscope. The results show that when the deposition time of Ti ions is 800 s, the thickness of the Ti film is 2.35 μm, the surface of the film is dense, and there are few defects. Meanwhile, Ti800 alloy has the best corrosion resistance among the four modified alloys. It has a corrosion current density (Icorr) of 2.9 μA·cm−2, which is about 50 times lower than that of unmodified alloy. This conclusion is also confirmed by the complete film layer of Ti800 alloy and the tight bonding with the substrate after immersion experiments. Good corrosion resistance is attributed to a dense and relatively chemically stable TiO2/Ti structure in simulated body fluid corrosive media. [ABSTRACT FROM AUTHOR]

High-entropy alloys (HEAs) are highly anticipated because of their superb properties in strength, hardness, wear resistance, etc. However, compared with numerous studies on the design and properties of HEAs, the machinability research of HEAs is extremely rare, which limits the application of HEAs. In this work, grinding experiments of (FeCoNi)86Al7Ti7 dual-phase HEA workpieces were carried out, and the results are analyzed from a general machinability perspective (the machining parameters' effect on grinding force and surface roughness) to a more in-depth perspective, including grinding-induced changes in morphology and microstructure on the ground surface and subsurface. With scanning electron microscope (SEM) and electron backscatter diffraction (EBSD) information of subsurface, the deformation mechanisms have been studied, including the role of the second-phase (Ni2AlTi) in the grinding process, the material removal modes of the different phases, and the morphology of the nanoprecipitates in the matrix, based on the completely opposite properties of different phases in HEA. It is noticed that the hard and brittle property of the second phase brings support to the material, reduces the plastic deformation, and also makes its own removal brittle, while the plastic matrix experiences shear deformation in grinding, which makes the nanoprecipitates in it assume different morphologies. These detailed findings could be of help to understand the effect of grinding on material properties so as to improve the machining quality of this material. [ABSTRACT FROM AUTHOR]

Cu additions notably strengthen Al-Mg-Si and Al-Si-Mg alloys due to the dense precipitation of quaternary nano precipitates during ageing. However, the chemical evolution and mechanical behaviors of the quaternary micro-scale Q constituent phase occurring in cast and homogenized states have rarely been studied. Meanwhile, there exists a type of AlCuMgSi cluster in the cast state, which has been regarded as Q particles. The accurate identification of phase constituents is the basis for the future design of alloys with better performance. In our work, this type of cluster was revealed to consist of α-Al, θ-Al2Cu, Q, and Si phases through micro-to-atomic scale studies using scanning and transmission electron microscopes. The skeleton of the dendrite was θ phase. The second phases in the dendritic eutectic cluster dissolved quickly during a 4 h homogenization at 550 °C. The Q phase was found to effectively absorb the Fe impurities during casting and homogenization. As a result, the formation of other harmful Fe-rich intermetallics was suppressed. These Q constituent particles were observed to break into separate pieces in an intermediately brittle manner when compressed in situ in a scanning electron microscope. These findings provide insights into the thermodynamic modeling of the Al-Mg-Si-Cu system and alloy design. [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]

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]

In the current scenario, many researchers aspire to develop biodegradable material for biomedical implant applications. Magnesium (Mg)-based alloys are most promising materials since they have mechanical properties similar to human bone. In this study, Mg alloy AZ31 matrix was reinforced with a seashell powder (2 wt.%) and zirconium dioxide (10 wt.%) using bottom pouring stir casting furnace. Scanning electron microscope (SEM) with energy dispersive spectroscopy (EDS) images confirms the proper distribution of reinforcement throughout the matrix. This study analyzed the influence of WEDM process parameters for the material removal rate (MRR) and surface roughness (SR) of the proposed composite. According to Taguchi's L9 (3 3) orthogonal array the machining was performed to investigate the ideal machining parameters with a range of pulse current (I p) 6–8 amps, pulse-on time ( T on ) 5–15 μ s and pulse-off time ( T off ) 10–30 μ s, respectively. Analysis of variance (ANOVA) result confirms that I p (45.86%) has the most influencing parameter affecting the MRR and SR, followed by T on (25.10%) and T off (17.19%), respectively. Furthermore, Technique for Order Preference by Similar Ideal Solution (TOPSIS) and desirability approach was employed to find the optimal parameter combinations to attain the best combined output responses. [ABSTRACT FROM AUTHOR]

Chloride ions play an important role in the corrosion of bronze through their active reactivity to copper alloys. The corrosion behavior of bronze alloys in NaCl solution was investigated by using X-ray diffraction (XRD), a scanning electron microscope (SEM), and electrochemical tests, with a special emphasis on the corrosion resistance of the α and δ phases in Cu-20 wt%Sn bronze alloys. The experimental results show that the corrosion current density of Cu-20 wt%Sn bronze alloys increases from 1.1 × 10−7 A/cm2 to 2.7 × 10−6 A/cm2 with the increase in the chloride ion concentration from 10−3 mol/L to 1 mol/L. After a soaking duration of 30 days, the matrix corrosion depth reaches 50 μm. The α phase of the alloys is easily corroded in NaCl solution, while the δ phase with high Sn content has strong corrosion resistance. This study provides relevant data for the analysis and protection of ancient bronze alloys. [ABSTRACT FROM AUTHOR]

Mg-3Sn-1Mn-xLa alloy bars were prepared using backward extrusion, and the effects of the La content on the microstructures and mechanical properties of the alloy were systematically studied using an optical microscope (OM), X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and tensile tests. The results of this research show that the Mg2Sn phases were mainly formed at the α-Mg grain boundaries and within the grains in the Mg-3Sn-1Mn alloy. After adding a certain amount of La, the plate-shaped MgSnLa compounds consisting of Mg17La2, Mg2Sn, and La5Sn3 gradually disappeared in the α-Mg matrix and grain boundaries. With an increase in La content, the Mg2Sn phase in the crystal was gradually refined and spheroidized. When the content of La reached 1.5%, the tensile strength of the alloy reached 300 Mpa and the elongation reached 12.6%, i.e., 25% and 85% increases, respectively, compared to the Mg-3Sn-1Mn alloy. The plate-shaped compound of Mg-3Sn-1Mn-1.5La had an average length of 3000 ± 50 nm, while the width was 350 ± 10 nm. Meanwhile, the extruded alloy's grain size was significantly refined, and there were many small cleavage steps and dimples in the fracture surface of the alloy. When the La content reached 2%, the alloy performance showed a downward trend due to the coarsening of the grains. The formed plate-shaped MgSnLa compounds and Mg2Sn phases were consistent with the α-Mg matrix. They effectively pinned the dislocations and grain boundaries, which is the main reason for strengthening the mechanical properties of extrusion alloys. [ABSTRACT FROM AUTHOR]

Mg77+xNi20−xLa3 (x = 0, 5, 10, 15) alloys were successfully prepared by the vacuum induction melting method. The structural characterizations of the alloys were performed by using X-ray diffraction and scanning electron microscope. The effects of nickel content on the microstructure and hydrogen storage kinetic of the as-cast alloys were investigated. The results showed that the alloys are composed of a primary phase of Mg2Ni, lamella eutectic composites of Mg + Mg2Ni, and some amount of LaMg12 and La2Mg17. Nickel addition significantly improved the hydrogen-absorption kinetic performance of the alloy. At 683 K, Mg77Ni20La3 alloy and Mg82Ni15La3 alloy underwent hydrogen absorption and desorption reactions for 2 h, respectively, and their hydrogen absorption and desorption capacities were 4.16 wt.% and 4.1 wt.%, and 4.92 wt.% and 4.69 wt.%, respectively. Using the Kissinger equation, it was calculated that the activation energy values of Mg77Ni20La3, Mg82Ni15La3, Mg87Ni10La3 and Mg92Ni5La3 alloys were in the range of 68.5~75.2 kJ/mol, much lower than 150~160 kJ/mol of MgH2. [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]

The article presents a precise method for the orientation process of NiMnGa-based single crystals. For this method, a scanning electron microscope equipped with an EBSD camera and a heating stage allowing temperatures exceeding 873 K was used. The orientation process was carried out in both the high-temperature austenite phase and in the room-temperature martensite phase. The facilities allowed for determining the orientation of a single grain of austenite at elevated temperatures as well as the orientation of particular martensitic variants at room temperature. A practically perfect cubic orientation was obtained in the austenitic case with a deviation of about 1° while the samples oriented in the martensitic phase deviated from the desired orientation by 4.5-5.2°. Additionally, the training process of single crystals was carried out in order to show the influence of the orientation process on twinning stress. [ABSTRACT FROM AUTHOR]

The new technology of mineral wool production with Nickel–Iron alloy waste residue has excellent prospect of development and application. The viscosity and crystallization behavior of Nickel–Iron alloy waste residue significantly influence the production process of the mineral wool. In current work, the influences of basicity on the viscosity and crystallization for four Nickel–Iron alloy waste residues have been investigated by confocal scanning laser microscope and viscometer, respectively. The crystals morphologies are characterized by field scanning electron microscope, and the compositions are analyzed by energy dispersive spectroscopy. According to the results, it is obvious that the experimental slag crystallization behaviors are consistent with crystallization kinetic model (Johnson-Mehl-Avrami equation). The crystallization rate, the crystal size, and the crystallization ability of Nickel–Iron alloy waste residue increases with increasing the slag basicity from 0.03 to 0.53. The main crystalline product is protopyroxene for No. 1 and No. 2 slags, and olivine for No. 3 and No. 4 slags. However, the viscosity of Nickel–Iron alloy waste residue decreases with the increase of basicity. The precipitation process of crystal has great influence on the viscosity of slag, and the influence degree of different crystal types is different. When the crystals in the slag grow up to a certain extent, the viscosity of the slag will increase dramatically. [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]

Magnesium-based alloys were more prevalent in automobile applications owing to their mechanical properties, low mass, and density. However, its poor mechanical properties are restricting its applications. Therefore, the present study focuses on improving the mechanical properties of AZ31D alloy by reinforcing silicon carbide (SiC) and graphite (Gr) nanoparticles with weight fractions of 2%, 4%, and 6% using stir-casting technique. The microstructure analysis was performed using a scanning electron microscope. The elemental analysis was confirmed using energy-dispersive spectroscopy, and X-ray diffraction was used to study various phases in the nanocomposites. Further, the mechanical properties, such as microhardness, ultimate tensile strength, yield strength, and compression strength of the nanocomposites, were significantly improved by 53%, 59%, 62%, and 82%, respectively, as compared with base alloy. [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]

The as-received AZ91D Mg alloy was coated with ZrO2 and ZrN ceramics using the Physical Vapour Deposition (PVD) process. Dry sliding wear investigations were performed in a pin-on-disc wear tester at a sliding velocity of 2-8 m/s and a normal load of 2-10 N. The wear mechanisms such as abrasion, delamination, thermal softening, and oxidation were observed. The results showed that PVD coating increased the wear resistance of AZ91D Mg alloy. The worn surface was examined with Scanning Electron Microscope (SEM). [ABSTRACT FROM AUTHOR]

The main aim of this research is to analyze the mechanical performances of the influence of silicon carbide (SiC) particles with AA6351 aluminum alloy. The aluminum metal matrix composites were prepared with liquefying stir casting to produce the metal matrix composites (MMCs). The following weight fractions are AA6351-0% SiC, AA6351-2.5% SiC, AA6351-5% SiC, and AA6351-7.5% SiC utilized to compose the MMCs. The mechanical performances like hardness, flexural, impact, compressive, and tensile studies were investigated on the processed MMCs. The scanning electron microscope (SEM) was employed to examine the strengthened particle of SiC. During the SEM examinations, uniformly dispersed SiC-strengthened particles were analyzed. The entire MMCs specimens achieve greater mechanical characteristics; the specimen fabricated with a maximum volume fraction of 7.5 wt% of SiC accumulates higher strength than the other volume fractions samples. The SiC plays a very tedious role in improving mechanical attributes. The fabricated MMCs were highly utilized in the applications of automotive and aerospace usages. This application is fully employed with lesser weight and maximum strength conditions to fulfill the mechanical performances. The stir-casting process was a highly efficient technique to compose better MMCs to achieve greater strength. [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 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]

In this study, to improve the corrosion protection system of Mg–Li alloy, Magnesia–alumina Layered double hydroxide (Mg–Al LDH) films were prepared on the LA103Z magnesium–lithium (Mg–Li) alloy by the in situ hydrothermal method. Subsequently, the microstructure of the Mg–Al LDH films was characterized by scanning electron microscope, X‐ray spectrometer, X‐ray diffraction, Fourier‐transform infrared spectroscopy, and the effect of different hydrothermal temperatures on the growth of the film was studied. Electrochemical impedance spectroscopy (EIS) and hydrogen evolution test were used to study the corrosion behavior of the films, revealing the anticorrosion mechanism of the films. The results show that the LDH film is in the form of a sheet‐like structure that crosses vertically on the LA103Z substrate. With the increase of the hydrothermal temperature, the size of the Mg–Al LDH sheet increases, and the distribution is denser. Electrochemical tests showed that the coated samples had significantly improved impedance modulus (|Z|) and charge transfer resistance (Rt) compared to bare samples. The potentiodynamic polarization curves demonstrated that the Mg–Al LDH film can effectively improve the corrosion resistance of the LA103Z magnesium alloy substrate. [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 paper aims to investigate the influence of silver addition on the microstructure of CuNi2Si1 alloys. The investigated copper alloy was cast and then supersaturated, plastically deformed on the Gleeble 3800 simulator and finally aged. Structural changes were examined using optical microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Orientation mapping was completed with FEI Quanta 3D field emission gun scanning electron microscope (SEM) equipped with TSL electron backscattered diffraction (EBSD) system. The effect of structural and microstructural changes on hardness and conductivity was also investigated. Based on the mechanical tests it was found that the mechanical properties and conductivity are improved due to heat and plastic treatment. It was also found that the precipitation hardening raises the hardness to the level of 40% whilst an increase in conductivity by 20% is observed. [ABSTRACT FROM AUTHOR]

The purpose of this work is to study the influence of thermal effect on the surface morphology of the Fe–Cr–Al (Kh15Yu5) alloy foil and the elemental composition of the surface layers. Also, studies have been carried out on the physicochemical characteristics of the primary support with the deposited secondary support in the initial state and within the temperature range from 25 to 900 °C. The research was carried out on a JSM 6610 LV, JEOL scanning electron microscope with an installed INCA Energy 450 energy-dispersive microanalysis system. Before depositing secondary support (aluminum oxide), for a stronger adhesion to the foil metal, the foil surface was pretreated with a phosphating solution. It was found that during heating up the elemental composition of the surface layer of the Kh15Yu5-alloy foil does not remain constant and depends on the mode of thermal effect. This implies the possibility of changing the adhesion and adsorption properties of the foil surface, as well as the need to take this into account when depositing secondary support and an active phase to the foil. Studies have shown that the applied methods for phosphatizing and depositing secondary support to the foil surface make it possible to obtain a quite resistant coating. No peeling of the secondary support from the foil surface is observed during high-temperature treatment in the air. [ABSTRACT FROM AUTHOR]

Cu–9Ni–6Sn alloys have received widespread attention due to their good mechanical properties and resistance to stress relaxation in the electronic and electrical industries. The hot compression deformation behaviors of the Cu–9Ni–6Sn–0.3Mn–0.2Zn alloy were investigated using the Gleeble-3500 thermal simulator at a temperature range of 700–900 °C and a strain rate range of 0.001–1 s−1. The microstructural evolution of the Cu–9Ni–6Sn alloy during hot compression was studied by means of an optical microscope and a scanning electron microscope. The constitutive equation of hot compression of the alloy was constructed by peak flow stress, and the corresponding 3D hot processing maps were plotted. The results showed that the peak flow stress decreased with the increase in the compression temperature and the decrease in the strain rate. The hot deformation activation energy was calculated as 243.67 kJ/mol by the Arrhenius equation, and the optimum deformation parameters for the alloy were 740–760 °C and 840–900 °C with a strain rate of 0.001~0.01 s−1. According to Deform-3D finite element simulation results, the distribution of the equivalent strain field in the hot deformation samples was inhomogeneous. The alloy was more sensitive to the deformation rate than to the temperature. The simulation results can provide a guideline for the optimization of the microstructure and hot deformation parameters of the Cu–9Ni–6Sn–0.3Mn–0.2Zn alloy. [ABSTRACT FROM AUTHOR]

This research mainly focuses on selecting phase change materials (PCM) and container materials for next-generation concentrated solar power plants (CSP). The present study investigates the hot corrosion behaviour of Inconel 617 and 625 in Na2SO4 + 45 wt-% diatomite PCM environment at 800°C for 40, 80 and 120 h. Oxide scales developed on the alloy surfaces were examined by Scanning electron microscope (SEM) and X-ray diffraction (XRD) to study morphology and oxide phases. The result indicates that Inconel 617 and 625 weight changes were 1.239 and 0.925 mg cm−2 at 800°C for a maximum duration of 120 h. The dense oxide of Cr2O3 is formed on alloys 617 and 625, which gives better oxidation resistance in a PCM environment. Moreover, the Inconel 625 shows lesser weight gain compared to Inconel 617 due to the presence of higher wt-% of Cr in the alloy and Nb formation oxides reducing corrosion species diffusion rate. [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]

An amount of 100 dpa Si2+ irradiation was used to study the effect of transmutation rhenium content on irradiated microscopic defects and hardening in W-xRe (x = 0, 1, 3, 5 and 10 wt.%) alloys at 550 °C. The increase in Re content could significantly refine the grain in the W-xRe alloys, and no obvious surface topography change could be found after high-dose irradiation via the scanning electron microscope (SEM). The micro defects induced by high-dose irradiation in W and W-3Re alloys were observed using a transmission electron microscope (TEM). Dislocation loops with a size larger than 10 nm could be found in both W and W-3Re alloy, but the distribution of them was different. The distribution of the dislocation loops was more uniform in pure W, while they seemed to be clustered around some locations in W-3Re alloy. Voids (~2.4 nm) were observed in W-3Re alloy, while no void was investigated in W. High-dose irradiation induced obvious hardening with the hardening rate between 75% and 155% in all W-xRe alloys, but W-3Re alloy had the lowest hardening rate (75%). The main reasons might be related to the smallest grain size in W-3Re alloy, which suppressed the formation of defect clusters and induced smaller hardening than that in other samples. [ABSTRACT FROM AUTHOR]

This paper presents the new route of fabrication of H-AlSi24Cu3.8Mg0.8 alloy, assisted by ultrasonic vibration stirring and squeeze casting (UVSS). The primary objective of this investigation is to establish the tribological characteristics of the prepared aluminium alloy under dry, lubricated, and coated sliding conditions. Oil SAE20W40 is used as a lubricant and diamond-like carbon (DLC) is used as a coating. Under a load between 20 N and 50 N, a linear reciprocating tribometer (LRT) with a ball-on-plate geometry is used. Alloy was examined using an optical microscope, scanning electron microscope with EDS, 3D surface profilometer, Brinell hardness tester, and tensometer for pre- and postcharacterization of alloy, surface, and worn tracks. The DLC-coated condition yields the lowest wear and coefficient of friction. [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]

In this study, the effect of aging at different temperatures and times on the properties of AA7075-T6 alloy was investigated. The samples prepared for the experimental studies were subjected to the solution, quenching, and then aging heat treatment at 100 °C and 200 °C for different periods (42-66-90 hours). The properties of the experimental samples were investigated by hardness, compression test, and scanning electron microscope (SEM). As a result of the studies, it was determined that the aging heat treatment had a positive effect on the microstructure and mechanical properties of the AA7075 alloy compared to the reference sample. Especially as a result of the heat treatments at 100 °C, higher results were obtained in hardness and compression strength compared to the initial values. [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]

Ti-6Al-4V is an α+β phase Ti alloy which is widely used because of its microstructural features. Complex three-dimensional (3-D) parts can be created directly from computer models by selectively melting (SLM) the metal powder using additive manufacturing (AM) technology. In this present work hot corrosion experiments were performed on the selective laser melted sample and as received sample in laboratory air and NaCl environment at 600°C for 50 cycles. The parabolic rate constants were calculated for different environments from the thermogravimetric data obtained for the samples and they show that corrosion rate is minimum in laboratory air and maximum for SLM sample in NaCl environment due to the presence of gaseous chlorides. The microstructure morphologies and the oxide scales formed upon hot corrosion was characterized by optical and scanning electron microscope (SEM) while the constituents were determined with energy-dispersive X-ray (EDX) analysis to understand the corrosion mechanisms. The high corrosion rate of SLM compared to the as-received sample was studied by analysing the area percentage of porosity. Since helicopters and planes are used in sea areas this work is practically important in the aeronautical field. [ABSTRACT FROM AUTHOR]