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Poly(vinyl chloride)/nitrile butadiene rubber (PVC/NBR) alloys were melt-mixed using a Brabender Plasticorder at 180°C and 50 rpm rotor speed. Alloys obtained by melt mixing from PVC and NBR were formulated with wood-flour- (WF-) based olive residue, a natural byproduct from olive oil extraction industry. WF was progressively increased from 0 to 30 phr. The effects of WF loadings on the tensile properties of the fabricated samples were inspected. The torque rheometry, which is an indirect indication of the melt strength, is reported. The pattern of water uptake for the composites was checked as a function WF loading. The fracture mode and the quality of bonding of the alloy with and without filler are studied using electron scanning microscope (SEM). [ABSTRACT FROM AUTHOR]

Directionally solidified samples of Mg-32.3 wt pct Al eutectic alloy were produced under an argon atmosphere in a vacuum Bridgman-type furnace to study the eutectic growth with different growth velocities. Typical features such as steady-state lamellar eutectic growth, lamellar branching at the quenching interface, and the formation of colony structures due to the impurity of the Mg-Al binary alloy were observed using a JEOL 6301F scanning electron microscope (JEOL Ltd., Tokyo, Japan). The lamellar spacing of the two eutectic phases was measured on the transverse sections of the samples. It was found that the relationship between the measured lamellar spacing and growth velocity agreed well with the prediction of the Jackson-Hunt model. Subsequent studies of Mg-Al eutectic growth were conducted using a numerical model based on the cellular automaton (CA) method. Taking account of the solute diffusion, constitutional undercooling, and curvature undercooling, modeling of steady-state lamellar eutectic growth was achieved. A systematic investigation of the eutectic growth morphology and lamellar spacing of the Mg-Al eutectic was carried out under directional solidification with different undercoolings, initial lamellar spacings, temperature gradients, and growth velocities. The results showed that under the interaction between solute diffusion and surface energy, the adjustment of eutectic lamellar spacing was accomplished by nucleation, lamellar branching, lamellar termination, and overgrowth. The simulated results were consistent with both the experimental results and the Jackson-Hunt eutectic theory. [ABSTRACT FROM AUTHOR]

A thin film of Zn-Ni-FeO on steel substrates was prepared by electrodeposition technique using Zn-Ni alloy plating solution with nano-sized FeO particles. The cathodic polarization and cyclic voltammetry techniques were used to explain deposition process. The corrosion behavior of deposits was evaluated by polarization and impedance studies. Scanning electron microscope (SEM) images were used to study the surface morphology of coating. The grain size and amount of FeO particles present in composite coating were measured by X-ray diffraction pattern (XRD) and energy dispersive X-ray diffraction spectrometer (EDS), respectively. [ABSTRACT FROM AUTHOR]

The fracture property improvement of Ni-Mn-Ga-Fe ferromagnetic shape memory alloys containing ductile γ particles was explained by direct observation of microfracture processes using an in-situ loading stage installed inside a scanning electron microscope (SEM) chamber. The Ni-Mn-Ga-Fe alloys contained a considerable amount of γ particles in β grains after the homogenization treatment at 1073 K to 1373 K (800 °C to 1100 °C). With increasing homogenization temperature, γ particles were coarsened and distributed homogeneously along β grain boundaries as well as inside β grains. According to the in-situ microfracture observation, γ particles effectively acted as blocking sites of crack propagation and provided the stable crack growth, which could be confirmed by the R-curve analysis. The increase in fracture resistance with increasing crack length improved overall fracture properties of the Ni-Mn-Ga-Fe alloys. This improvement could be explained by mechanisms of blocking of crack propagation and crack blunting and bridging. [ABSTRACT FROM AUTHOR]

In this study, the effect of Sn addition on the microstructure and dry sliding wear behaviors of as-cast and heat-treated hypereutectic A390 alloys was investigated. The microstructural features of the alloys were characterized by means of optical microscope, scanning electron microscope (SEM), and energy dispersive X-ray spectroscopy techniques and their wear characteristics were evaluated at different loads. The worn morphologies of the wear surface were examined by SEM. The results show that the β-Sn in as-cast A390 alloy precipitates mainly in the form of particles within the AlCu network on the interface of the eutectic silicon and α-Al phases and the grain boundaries of α-Al phase. The addition of Sn promotes the disintegrating and spheroidizing of both the eutectic and primary silicon of the A390 alloy during solid solution-aging treatment and β-Sn phase grains coalesces and grows, and some of them form the structure of Sn wrapping Si. The wear rates and friction factors of the as-cast and heat-treated A390 alloys with Sn are lower than those without Sn. At lower load, the addition of Sn changes the wear mechanism of as-cast A390 alloy from the combination of abrasive and adhesive wear without Sn into a single mild abrasion wear with Sn; at higher load, the wear of as-cast A390 alloy without Sn includes abrasion, adhesive, and fatigue one, while the addition of Sn effectively restrains the net-like cracks on the worn surface of the alloy and avoids the fatigue wear emerged. [ABSTRACT FROM AUTHOR]

The purpose of this study is to explore the effect of SiC reinforcement along with immiscible element addition in spray formed Al-Si base alloy. The investigation is done for four different compositions, i.e., Al-Si base alloy, Al-Si/SiC, Al-Si-5Sn/SiC and Al-Si-10Sn/SiC composite. The dry sliding wear properties of base alloy and composites were investigated against EN 31 steel at five different normal loads (14.7, 24.5, 34.3, 44.1 and 53.9 N). The tests were carried out in dry sliding conditions with a sliding speed of 1.6 ms over pin-on-disc tribometer. Each composition is tested at four different temperatures 50, 75, 100 and 150 °C. To determine the wear mechanism, the worn surfaces of the samples were examined using scanning electron microscope (SEM). The composites emerge to be better wear resistant material than base alloy especially at higher loads. The optimum wear reduction was obtained in Al-Si-10Sn/SiC composite at all the different normal loads and temperatures. [ABSTRACT FROM AUTHOR]

Vitallium-2000 Plus alloy is one of the important metallic biomaterials having excellent biocompatibility as it is free from nickel, vanadium, and beryllium elements that could cause potential allergic problems to patients. In this study, the high cycle fatigue behavior of continuous cast vitallium-2000 Plus alloy was investigated using rotation bend fatigue tests at 50 Hz frequency and at room temperature apart from tensile studies. A series of tests were carried out at varying stresses, and the S-N curve was obtained from regression of the test data. The endurance limit was determined as 387 MPa, which is very good for a cast alloy. This increase in fatigue property (compared to the previous version of this alloy) is primarily due to the presence of nitrogen that is added during continuous casting process and also that of the other alloying elements. Tensile test was also performed as per the ASTM standard to evaluate its static properties. The fracture morphology was investigated using scanning electron microscope to study the mechanisms of fracture. It was established that the primary mechanism of fracture was by microvoid nucleation and coalescence, typical of a ductile material that is significant for a cast alloy. The experimentally determined values of endurance limit, yield strength, tensile strength, and percent elongation provide evidence that vitallium-2000 Plus cast alloy has very good fatigue, tensile properties, and increased formability without fracture, allowing for excellent adjustability during its application. [ABSTRACT FROM AUTHOR]

In this study, abrasive wear behaviours of ZA-27 alloy and CuSn10 bronze were investigated using a purpose-built wear tester. The ZA-27 alloy was produced by permanent mould casting. The abrasive SiC particles having 63 μm grit size was added to the lubricant oil. The wear rate and friction coefficient of alloys were determined at the different test conditions such as sliding distance, applied load, linear velocity and percentage SiC weight content. The wear surfaces of alloys were examined using SEM and EDS analysis. The results showed that the wear rate of alloys decreased with the increasing of applied load and increased with the increasing linear velocity and abrasive SiC content. It was found that the SiC particle fracture was an important mechanism determining the friction and the wear rate of alloys. CuSn10 bronze showed higher wear resistance than ZA-27 alloy under abrasive test conditions except at high linear velocities. [ABSTRACT FROM AUTHOR]

the miniaturization trend of electronic packing industry, electromigration (EM) has become a critical issue for fine pitch packaging. The EM effects on microstructure evolution of intermetallic compound layer (IMC) in Sn-3.0 Ag-0.5 Cu + XCo ( X = 0, 0.05, 0.2 wt%) solder joint was investigated. Findings of this study indicated that current stressing of Sn-3.0 Ag-0.5 Cu-0.2 Co solder joint with 10 A/cm at 50 °C for 16 days, no remarkable EM damages exhibited in solder matrix. Whereas, after current stressing at 150 °C for 1 and 3 days, Sn-3.0 Ag-0.5 Cu specimens showed obvious polarity effect between cathode and anode. Different morphology changes were also observed at both sides. After current stressing for 1 day, two IMC layers, CuSn and CuSn, with wave type morphology formed at cathode. Sn phases were also observed inside in the IMC layer. However, only CuSn formed in anode. Three days later, Sn phases were found in anode. Besides, Co additions, aging treatment, AgSn, and other IMCs improved the resistance of EM by the evidence of retarding polarity effect. [ABSTRACT FROM AUTHOR]

This paper discusses the effect of stanum (Sn) addition on the physical properties of Al-5.5Zn-2.0Mg-xSn (where x = 0.1 - 2.0 wt. %) alloys. These alloys were prepared using conventional casting techniques. The phases, microstructures, hardness and electrical resistivity of as-cast and heat-treated Al-5.5Zn-2.0Mg-xSn alloys were characterised using a con focal laser scanning microscope (CLSM), an x-ray diffractometer (XRD), a four point probe resistivity meter and a scanning electron microscope (SEM). The hardness of heat-treated Al-5.5Zn-2.0Mg-xSn alloys was much better than that of as-cast alloys mainly due to the dispersive distribution of Mg2Sn phase in the aging-treated alloy. The calculated hardness values for both as-cast and heat treated Al-5.5Zn-2.0Mg-xSn alloys suggest that the decrease of hardness value with increasing Sn contents can be ascribed to formation of more Mg2Sn intermetallic compound in these alloys. Electrical resistivity measurement shows a decrease in both as-cast and heat-treated alloys with decreasing Sn content in these alloys. It was concluded that the addition of Sn gives a strong influence on the formation of strengthening precipitates and electron mobility in the Al-5.5Zn-2.0Mg-xSn alloys. [ABSTRACT FROM AUTHOR]

Titanium-nickel (TiNi) shape memory alloy is modified with tantalum (Ta) plasma immersion ion implantation (PIII). Scanning electron microscope (SEM), atomic force microscopy (AFM), inductively coupled plasma mass spectrometry (ICP-MS), methyl-thiazol-tetrazolium (MTT), and cell culture are adopted to evaluate the surface morphology, roughness, Ni release, in vitro cytotoxicity, and cell behavior of TiNi and Ta-implanted TiNi (Ta-TiNi) alloys. Results showed that the surface became rougher and was covered by ordered and uniform grains after Ta implantation. Ni release was averagely inhibited by Ta-TiNi to up to 60% of that in unmodified TiNi alloy within 30 days. MTT assays demonstrated that Ta-TiNi sample allowed greater degree of cell proliferation for both smooth muscle cell and osteoblasts, indicating excellent protection and cyto-compatibility. A negative correlation was observed between Ni release and cell proliferation. Analysis of the cell morphology revealed healthy cells extending on the alloy surface, which indicated that TiNi alloy had good cyto-compatibility despite the initial Ni dissolution, but the implanted Ta would endow traditional TiNi alloy much lower Ni release, improved cyto-compatibility and other potential merits. [ABSTRACT FROM AUTHOR]

Abstract: The influence of the quantity of the Mg2Sn phase on the corrosion behavior of different solution temperature treated Mg–7Sn magnesium alloy has been investigated by electrochemical measurements, scanning electron microscope (SEM) observation, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis. With the increase of solution temperature, the quantity of Mg2Sn phase decreased and the tin concentration of matrix increased. The dissolved tin in Mg matrix took part in the film formation and the constituent of film was magnesium oxide and stannic oxide. The corrosion mode and corrosion rate were associated with the quantity of Mg2Sn phases and tin concentration of the matrix. If most of tin was present as Mg2Sn, the corrosion mode was pitting corrosion and it accelerated the corrosion rate. If most of tin was dissolved in matrix, the corrosion mode was filiform corrosion and it decreased the corrosion rate. The experiment evidences demonstrated that the corrosion resistance can be improved by increasing the tin concentration of matrix and the lowest corrosion rate was observed for sample solution treated at 540°C. [Copyright &y& Elsevier]

Abstract: Laser cladding of the Al+TiC alloy powder on Ti–6Al–4V alloy can form the Ti3Al/TiAl+TiC ceramic layer. In this study, TiC particle-dispersed Ti3Al/TiAl matrix ceramic layer on the Ti–6Al–4V alloy by laser cladding has been researched by means of X-ray diffraction, scanning electron microscope, electron probe micro-analyzer, energy dispersive spectrometer. The main difference from the earlier reports is that Ti3Al/TiAl has been chosen as the matrix of the composite coating. The wear resistance of the Al+30wt.% TiC and the Al+40wt.% TiC cladding layer was approximately 2 times greater than that of the Ti–6Al–4V substrate due to the reinforcement of the Ti3Al/TiAl+TiC hard phases. However, when the TiC mass percent was above 40wt.%, the thermal stress value was greater than the materials yield strength limit in the ceramic layer, the microcrack was present and its wear resistance decreased. [ABSTRACT FROM AUTHOR]

The 300 series stainless steels generally exhibit good corrosion resistance in common use. However, a premature fracture event caused by hydrogen embrittlement was encountered on 300 series stainless steels which was used as belt hanging chips in a tin plating process for the chip lead frame. The cause of the fracture was carefully studied. A metallurgical microscope and photoelectric direct reading spectrometer were used to examine the metallographic structures and chemical compositions of the matrix material. A scanning electron microscope and energy disperse spectroscope were also applied to analyze the micro morphologies and micro-area composition of the fracture. Meanwhile, the chemistry and hydrogen content of the process media were inspected by ion chromatography and hydrogen analyzer. In addition, the finite element method was employed to simulate the effect on the belt from the service conditions. The analysis results revealed that the unqualified material selection, the aggressive media, and the inappropriate technological parameters were the main causes of the failure. Furthermore, the mechanisms of hydrogen embrittlement were discussed, and countermeasures and suggestions were put forward. [ABSTRACT FROM AUTHOR]

By using Au58.74Ni36.50V4.76 at.% filler alloy, a reliable Si3N4/Si3N4 joint was brazed at 1,423 K for 60 min in vacuum. The microstructure of the joint was investigated and analyzed by scanning electron microscope with energy dispersive spectroscopy, transmission electron microscopy, and X-ray diffraction. The results indicate that the joint consists of three main phases: a continuous VN reaction layer between filler alloy and Si3N4 ceramic; an Au[Ni] solid solution as the matrix of the joint; and Ni[Si,V] solid solution particles distributed homogeneously in the Au[Ni] solid solution. The mechanism of formation of the interfacial structure is discussed. [ABSTRACT FROM AUTHOR]

The solidification paths of the Al86.1Mn2.5Be11.4 and Al84Mn5.1Be10.9 alloys, melt spun, cast into a copper mould and controlled cooled (during DSC) were investigated by means of light-optical microscopy (LOM), differential scanning calorimetry (DSC) combined with thermogravimetry (TG) or simultaneous thermal analysis (STA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Auger electron spectroscopy (AES) and the X-ray diffraction (XRD) line in Elletra Trieste, Italy. The con- stitutions of samples from both alloys were examined in all three states, i.e., after melt spinning, after casting into a copper mould and after differential scanning calorimetry. It was established that in the cast and controlled-cooled specimens the alloys consisted of an aluminium-rich αAI-matrix, and the AI4Mn and Be4AIMn phases. In the case of casting and DSC the primary crystallization began with the precipitation of the Be4AlMn phase, followed by what can most likely be characterized as a uni-variant binary eutectic reaction L→ (Be4AlMn + Al4Mn). The solidification process continued with an invariant ternary eutectic reaction, where the remaining melt (L) formed the heterogeneous structure (αAI + AI4Mn + Be4AIMn) or a ternary eutectic. When extremely high cooling rates were employed, as is the case with melt-spinning, the constituting phases of both alloys were precipitated in a very small form and the Be4AIMn phase was completely absent in the form of primary polygonal particles and replaced by the icosahedral quasicrystal- line phase or the i-phase. There was also no evidence of the AI4Mn phase. The distribution, size and shape of all the constituents in the melt-spun alloys also varied from the contact surface towards the free surface of the ribbons. The smallest constituents were established at the contact surface, measuring less than 0.1 μm, to 0.5 μm at the free surface. The grains of the aluminium-rich matrix had mean diameters of less than 20 μm, close to the free surface, down to 1 μm at the contact surface. [ABSTRACT FROM AUTHOR]

Abstract: In order to improve the hydriding and dehydriding kinetics of the Mg2Ni-type alloys, Ni in the alloy was partially substituted by element Cu, and the nanocrystalline Mg2Ni-type Mg20Ni10−xCux (x = 0, 1, 2, 3, 4) alloys were synthesized by melt-spinning technique. The structures of the as-cast and spun alloys were studied by XRD, SEM and HRTEM. The hydrogen absorption and desorption kinetics of the alloys were measured using an automatically controlled Sieverts apparatus. The results show that the substitution of Cu for Ni does not change the major phase Mg2Ni. The hydrogen absorption capacity of the alloys first increases and then decreases with rising Cu content, but the hydrogen desorption capacity of the alloys grows with increasing Cu content. The melt spinning significantly improves the hydrogenation and dehydrogenation capacity and kinetics of the alloys. [Copyright &y& Elsevier]

Electromagnetic levitation (EML) has been used as an experimental technique for investigating the effect of the nucleation and cooling rate on segregation and structure formation in metallic alloys. The technique has been applied to aluminum-copper alloys. For all samples, the primary phase nucleation has been triggered by the contact of the levitated droplet with an alumina plate at a given undercooling. Based on the recorded temperature curves, the heat extraction rate and the nucleation undercooling for the primary dendritic and the secondary eutectic structures have been determined. Metallurgical characterizations have consisted of composition measurements using a scanning electron microscope (SEM) equipped with energy dispersive X-ray spectrometry and the analysis of SEM images. The distribution maps drawn for the composition, the volume fraction of the eutectic structure, and the dendrite arm spacing (DAS) reveal strong correlations. Analysis of the measurements with the help of a cellular-automaton (CA)–finite-element (FE) model is also proposed. The model involves a new coupling scheme between the CA and FE methods and a segregation model accounting for diffusion in the solid and liquid phases. Extensive validation of the model has been carried out on a typical equiaxed grain configuration, i.e., considering the free growth of a mushy zone in an undercooled melt. It demonstrates its capability of dealing with mass exchange inside and outside the envelope of a growing primary dendritic structure. The model has been applied to predict the temperature curve, the segregation, and the eutectic volume fraction obtained upon single-grain nucleation and growth from the south pole of a spherical domain with and without triggering of the nucleation of the primary solid phase, thus simulating the solidification of a levitated droplet. Predictions permit a direct interpretation of the measurements. [ABSTRACT FROM AUTHOR]

Microhole drilling and microstructure machining with a picosecond (ps) Nd: YVO4 laser (pulse duration of 10 ps) in metals, alloys, and ceramics are reported. Blind and through microholes are drilled by percussion drilling as well as trepanning drilling, where the diameters of the holes are in the range of 20-1000 μm. Microfeatures are also machined and the flexibility of ps laser machining is demonstrated. The quality of drilled holes, e.g., recast layer microcrack, and conicity, and that of the microstructures, are investigated by an optical microscope, a surface profilometer, or a scanning electron microscope. Ps laser ablation rate is studied by experiments and a simplified laser ablation model. [ABSTRACT FROM AUTHOR]

Purpose: This study evaluated the effect of three metal conditioners [Metal Photo Primer® (MPP), Cesead II Opaque Primer® (OP), Targis Link® (TL)], and one surface modification system [Siloc® (S)] on the shear bond strength (SBS) of a prosthetic composite material to Ni-Cr alloy. Materials and Methods: Rivet-shaped specimens were cast, and three surface treatments were evaluated: Polishing (P); sandblasting with either 50 μm (50SB) or 250 μm (250SB) Al2O3. All products were applied to half of the specimens, while the other half remained without the materials. Veneering resin composite (8-mm diameter, 2-mm thick) was applied and light-exposed for 90 seconds in a laboratory light-curing unit. The specimens were stored in water at 37°C for 24 hours, and half were subjected to 500 thermal cycles consisting of water baths at 4°C and 60°C. All specimens were submitted to SBS test (0.5 mm/min) until failure. Failure patterns were determined using optical and scanning electron microscope (SEM) analysis. Data were analyzed by ANOVA and post hoc Tukey's test (preset alpha of 5%). Results: The SBS values of OP and TL groups were higher than those of MPP and S within the 50SB treatment ( p < 0.05). No significant difference in SBS was noted between OP and TL as well as between MPP and S. On the other hand, no significant differences were found among conditioners within the 250SB group ( p > 0.05). The SBS values of MPP, OP, and S from the 250SB group were higher than those from 50SB ( p < 0.05). No significant difference in SBS was noted among most groups with conditioners after thermocycling. The only exception was observed for MPP, which showed an increase in SBS after thermocycling ( p < 0.05). Differences in SBS were noted among the groups with conditioners ( p < 0.05), and no significant difference in SBS was noted between TL and OP groups, which showed the highest values among all within the P group. No significant difference was noted between MPP and S. Debonded surfaces showed adhesive failures predominantly located between metal surface and opaque resin. Conclusions: The OP and TL conditioners and surface sandblasting with 250 μm Al2O3 promoted the highest SBS between resin and the Ni-Cr metal surface. [ABSTRACT FROM AUTHOR]

Abstract: The effect of concentration on the corrosion behavior of Mg-based alloy AZ91D was investigated in ethylene glycol–water solutions using electrochemical techniques i.e. potentiodynamic polarization, electrochemical impedance measurements (EIS) and surface examination via scanning electron microscope (SEM) technique. This can provide a basis for developing new coolants for magnesium alloy engine blocks. Corrosion behavior of AZ91D alloy by coolant is important in the automotive industry. It was found that the corrosion rate of AZ91D alloy decreased with increasing concentration of ethylene glycol. For AZ91D alloy in chloride >0.05M or fluoride <0.05M containing 30% ethylene glycol solution, they are more corrosive than the blank (30% ethylene glycol–70% water). However, at concentrations <0.05 for chloride or >0.05M for fluoride containing ethylene glycol solution, some inhibition effect has been observed. The corrosion of AZ91D alloy in the blank can be effectively inhibited by addition of 0.05mM paracetamol that reacts with AZ91D alloy and forms a protective film on the surface at this concentration as confirmed by surface examination. [Copyright &y& Elsevier]

In the present work, time of calcium phosphate formation on Ti6Al4V alloy with or without alkali and heat treatments was investigated. Specimens were soaked in 0, 5 and 10M solutions of NaOH at temperatures of 60 and 80°C for 1 and 3 days and then their surfaces were characterised by using scanning electron microscopy and thin film X-ray diffraction. It was found that optimum condition is 3 days soaking in 5M NaOH in 80°C. Specimens treated under these optimum conditions were subsequently heat treated at 500, 600 and 700°C for 1 h to consolidate the sodium titanate hydrogel layer. With heat treatment at 600°C for 1 h and then soaking in simulated body fluid, apatite formed within 3 days. However, there were no signs of apatite formation in control samples (without alkali and heat treatment) up to 7 days soaking in SBF. [ABSTRACT FROM AUTHOR]

In this article, the effect of aging time in Al-Li-Hf alloy was studied. The samples were homogenized at 600°C and aged from 0.166 to 100 h at 190°C in thermal oil. According to scanning electron microscope (SEM) images, the effect of aging in the intermetalic precipitates changes its morphology as well as composition. For as cast alloys small Hf-Li precipitates with high Hf content exist. When considering aging samples the size precipitates increases, as does Hf content, from 30.74% for 1 h to 59.85% for 100 h. For an aging time of 100 h, the microhardness Vickers show better values which can be attributed to the Hf-Li solubility into the Al matrix to the point where their precipitation of intermetalic precipites and further cause changes in the dendritic arm spacing. [ABSTRACT FROM AUTHOR]

The article presents a study on the nanoparticles' melting temperature in the new tin-cobalt-copper (Sn-Co-Cu) lead-free solder alloy. The study employs ultrasonic vibration, field emission scanning electron microscope, differential scanning calorimetry, and X-ray diffraction. The study reveals that the melting temperature of nanoparticles was approximately 5° Celsius (C) lower than with the bulk alloy. The study suggests that the newly developed alloy offers cost advantage than the extensively used tin-silver-copper (Sn-Ag-Cu) system.

Abstract: The inhibition effect of glycine (Gly) towards the corrosion of low alloy steel ASTM A213 grade T22 boiler steel was studied in aerated stagnant 0.50M HCl solutions in the temperature range 20–60°C using potentiodynamic polarization (Tafel polarization and linear polarization) and impedance techniques, complemented with scanning electron microscope (SEM) and energy dispersive X-ray (EDX). Electrochemical frequency modulation (EFM), a non-destructive corrosion measurement technique that can directly give values of corrosion current without prior knowledge of Tafel constants, is also presented here. Experimental corrosion rates determined by the Tafel extrapolation method are compared with corrosion rates obtained by electrochemical, namely EFM technique, and chemical (i.e., non-electrochemical) method for steel in HCl. The chemical method of confirmation of the corrosion rates involved determination of the dissolved cation, using ICP-AES (inductively coupled plasma atomic emission spectrometry) method of analysis. Corrosion rates (in mm y−1) obtained from the electrochemical (Tafel extrapolation and EFM) and the chemical method, ICP, are in a good agreement. Polarization studies have shown that Gly is a good “green”, mixed-type inhibitor with cathodic predominance. The inhibition process was attributed to the formation of an adsorbed film on the metal surface that protects the metal against corrosive agents. Scanning electron microscopy (SEM) and energy dispersion X-ray (EDX) examinations of the electrode surface confirmed the existence of such an adsorbed film. The inhibition efficiency increases with increase in Gly concentration, while it decreases with solution temperature. Temkin isotherm is successfully applied to describe the adsorption process. Thermodynamic functions for the adsorption process were determined. [Copyright &y& Elsevier]

In this study, the Ti-6Al-4V alloy was diffusion bonded to austenitic stainless steel at temperatures of 820, 885, 930 and 980°C, under a pressure of 5 MPa for 30 min. The effect of temperature on interface formations and microstructure was investigated using a scanning electron microscope (SEM), energy dispersive spectrograph (EDS) microanalyses, X-ray diffraction and shear strength of bonded specimens. The results showed that intermetallic phases and a-phase formed in the interface region. [ABSTRACT FROM AUTHOR]

A novel as-cast Mg96.82Gd2Zn1Zr0.18 alloy was produced by conventional ingot metallurgy. By scanning electron microscope and transmission electron microscope observations, its as-cast microstructure is mainly composed of the α′-Mg solid solution, the coherent fine-lamellae and the eutectic. The β-phase ((Mg,Zn)3Gd) as the second phase in eutectic has a face-center cubic structure. While, the coherent lamellae consist of the 2H–Mg and the 14H-type long period stacking ordered (LPSO) structure. At present, the lamellar 14H-type LPSO structure has first been observed within α′-Mg matrix in the as-cast Mg–Gd–Zn–Zr alloys. It can be concluded that the lamellar 14H-type LPSO structure within α′-Mg matrix is a special structure obviously different from α-Mg matrix (2H-type structure) in structure, composition, and formation condition. [ABSTRACT FROM AUTHOR]

Aggregation of Y 2 O 3 particles with relatively large size along grain boundaries is a main limiting factor for performance improvement in W–Y 2 O 3 alloys. In order to tailor the distribution and achieve size refinement of Y 2 O 3 dispersoids, W–Y 2 O 3 alloy was prepared using ball milling with extended milling time and subsequent spark plasma sintering (SPS) in this study. Microstructure evolution of Y 2 O 3 during the preparation process was characterized in detail using X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). Mechanical properties of SPSed alloy were evaluated in terms of microhardness, three-point bending and compression tests. Structure transformation of Y 2 O 3 from BCC to FCC during the process of ball milling and subsequent sintering was first identified in W–Y 2 O 3 alloy in this study. Compared with the raw micron sized Y 2 O 3 powders, the transformed Y 2 O 3 dispersoids experienced significant size refinement. Around 76% of the nanosized Y 2 O 3 dispersoids were distributed inside grain interior, and they exhibited semi-coherent relationship with tungsten matrix. These microstructural characteristics contributed to the high compressive strength of 1804.2 MPa and microhardness of 625.7 HV in the SPSed W–Y 2 O 3 alloy. • W–Y 2 O 3 alloy were prepared by extended ball milling and SPS. • Structure transformation of Y 2 O 3 from BCC to FCC was identified in W–Y 2 O 3 alloy. • Y 2 O 3 also experienced size refinement and 76% of them were inside grain interior. • The nanosized Y 2 O 3 exhibited semi-coherent relationship with tungsten matrix. • Y 2 O 3 dispersoids contributed to improved strength mainly through grain refinement. [ABSTRACT FROM AUTHOR]

In this work, the effect of Cu on the phase transformation, microstructure, and properties of AlCrFeNiTiCux high-entropy alloys (HEAs) was investigated. Meanwhile, the formation mechanism of the FCC solid solution was discussed. The results showed that it was a beneficial effect on the formation of the FCC solid solution for the addition of Cu into HEAs from the perspective of valence electron concentration (VEC), enthalpy of mixing (ΔH mix) and difference in atom size (δ), which was confirmed by X-ray diffraction and Scanning Electron Microscope analysis. In addition, the increment of Cu content in the alloys promoting the segregation of Al, Ni and Ti in dendrite and Fe, Cr segregated into particles distributed in dendrite and inter-dendrite. The micro-hardness of the HEAs decreased with increasing Cu content and as the Cu content increased, oxidative wear intensified. However, the friction coefficient was significantly reduced, which was related to the lubricity of Cu itself. Besides, the segregation of Cu increased the corrosion current density of the passivation zone of the HEAs, thereby reducing the corrosion resistance of the HEAs in 0.5 mol/L H 2 SO 4 solution. • Added Cu promotes FCC phase forming. • Cu improves the wear resistance. • Cu element reduces the corrosion resistance. [ABSTRACT FROM AUTHOR]

In this study, Alloy 247LC samples were built with different laser powder bed fusion (L-PBF) process parameters. The samples were then subjected to solution heat treatment at 1260 °C for 2 h. The grain size of all the samples increased significantly after the heat treatment. The relationship between the process parameters and grain size of the samples was investigated by performing a design of experiment analysis. The results indicated that the laser power was the most significant process parameter that influenced the grain height and aspect ratio. The laser power also significantly influenced the grain width. The as-built and as-built + heat-treated samples with high, medium, and low energy densities were characterized using a field emission gun scanning electron microscope equipped with an electron backscatter diffraction detector. The micrographs revealed that the cells present in the as-built samples disappeared after the heat treatment. Isolated cases of twinning were observed in the grains of the as-built + heat-treated samples. The disappearance of cells, increase in the grain size, and appearance of twins suggested that recrystallization occurred in the alloy after the heat treatment. The occurrence of recrystallization was confirmed by analyzing the grain orientation spread of the alloy, which was lower and more predominantly <1° in the as-built + heat-treated conditions than in the as-built conditions. The microhardness of the as-built + heat-treated samples were high which was plausible because γ' precipitates were observed in the samples. However, the L-PBF process parameters had a very low correlation with the microhardness of the as-built + heat-treated samples. • The process parameter employed will affect the material condition obtained after heat-treatment. • The material condition that resisted cracking during the laser powder bed fusion process produced large grain size. • The heating rate required to avoid cracking during post processing heat-treatment was calculated. [ABSTRACT FROM AUTHOR]

In this research, an experimental evaluation of creep properties of Alloy 709 in the temperature range of 750–850 °C was undertaken. Alloy 709 is a novel austenitic stainless steel with 20% Cr and 25% Ni by wt% that was developed for application in structural components of nuclear power plants. Creep rupture tests were conducted in an in-situ heating-loading and Scanning Electron Microscope (SEM) unit equipped with Electron Backscatter Diffraction (EBSD) detector and Energy Dispersive Spectroscopy (EDS). "Real-time" creep damage mechanisms of Alloy 709 at various stresses and temperatures using a flat, un-notched sample with continuously reducing cross-section is studied so that the failure and maximum creep damage occurred at the center of the sample where the in-situ SEM imaging could be focused. Accelerated creep tests at temperatures and stresses above service conditions were performed by employing multiple blocks of constant loads where the loads were increased once the sample attained constant creep rate, indicating a secondary creep regime. This technique ensures multiple data points can be obtained from the same test, saves the time required for an otherwise long-term creep test and usage of SEM. Coincident Site Lattice (CSL) boundary maps were collected as control maps before testing, and the grain boundaries were observed during the creep test to understand the effect of grain boundary character on the creep damage mechanism. Void growth, grain boundary separation, and sliding were found to be the main creep mechanisms whose rate is dependent on stress and temperature. Failure mechanisms studied on the fracture surface using SEM fractography were correlated to the sample surface observations to create complementary information to better understand the underline creep mechanism of Alloy 709. [Display omitted] • Real-time creep mechanisms of Alloy 709 at various stresses & temperatures were studied using in-situ SEM. • Conventional creep-rupture tests and expedited creep rupture tests with multiple blocks of constant loads were conducted. • Nucleation and growth of voids, grain boundary separation, and sliding were observed • Void area fraction and creep rate were used to find creep parameters. • Creep life relations were established. [ABSTRACT FROM AUTHOR]

Abstract: Electroless nickel plating on Mg–8Li alloy was studied, and an appropriate molybdate pretreatment was proposed. The pretreatment layer acted as an effective barrier and catalytic layer for the subsequent Ni–P plating. The coating was characterized by its structure, morphology, micro-hardness and corrosion resistance. Scanning Electronic Microscope (SEM) observation showed that the Ni–P coating was compact, uniform. The presence of molybdate pretreatment layer could reduce the potential difference between the Ni–P coating and the substrate, and enhanced the corrosion resistance of the alloy to certain extent. The electrochemical measurements showed that the sample with Ni–P film exhibited lower corrosion current density and more positive corrosion potential than the substrate. The hydrogen evolution tests further proved that the Ni–P coating provided good protection to the substrate. [Copyright &y& Elsevier]

• Ti-6Al-4V were manufactured by the DMLS technique with different laser powers. • Effect of the microstructure and surface modifications on apatite formation ability was investigated in the SBF solution. • Ca and P ions ratios were calculated to determine the formation of apatite layer. • The samples 3 exhibited a higher apatite formation ability. [Display omitted] In this study, Ti-6Al-4V alloys were additively manufactured (AM) with different laser powers. The goal was to investigate the effect of different surface modifications on apatite formation ability. Four types of surface modifications, namely, sandblasting (S), acid etching (E), anodic oxidation (AO) and anodic spark oxidation (ASO), were achieved on the Ti-6Al-4V samples. The microstructure, phase, morphology, roughness and wettability properties were examined by optical microscope (OM), scanning electron microscope (SEM), X-ray diffraction (XRD), surface profilometer and contact angle techniques. The bioactivity analysis was performed in simulated body fluid (SBF) for 2 weeks. The results indicated that the microstructure, surface topography, roughness and wettability influenced the apatite formation were affected by the production laser power. Generally, the samples 3 showed higher Ca and P ion ratio value because of percentage of β phase amount, the presence of bioactive phases on the surfaces. The E3 sample resulted in the best apatite formation theoretically. The etching procedure of AM Ti-6Al-4V in the acidic solution can be applied to improve the apatite formation ability of Ti-6Al-4V alloys. [ABSTRACT FROM AUTHOR]

Titanium (Ti)-based alloys (e.g., Ti6Al4V) are widely used in orthopedic implant applications owing to their excellent mechanical properties and biocompatibility. However, their corrosion resistance needs to be optimized. In addition, the presence of aluminum and vanadium cause alzheimer and cancer, respectively. Therefore, in this study, titanium-based alloys were developed via powder metallurgy route. In these alloys, the Al and V were replaced with tin (Sn) which was the main aim of this study. Four sets of samples were prepared by varying Sn contents, i.e., 5 to 20 wt. %. This was followed by characterization techniques including laser particle analyzer (LPA), X-ray diffractometer (XRD), scanning electron microscope (SEM), computerized potentiostate, vicker hardness tester, and nanoindenter. Results demonstrate the powder sizes between 50 and 55 µm exhibiting very good densification after sintering. The alloy contained alpha at all concentrations of Sn. However, as Sn content in the alloy exceeded from 10 wt. %, the formation of intermetallic compounds was significant. Thus, the presence of such intermetallic phases are attributed to enhanced elastic modulus. In particular, when Sn content was between 15 and 20 wt. % a drastic increase in elastic modulus was observed thereby surpassing the standard/reference alloy (Ti6Al4V). However, at 10 wt. % of Sn, the elastic modulus is more or less comparable to reference counterpart. Similarly, hardness was also increased in an ascending order upon Sn addition, i.e., 250 to 310 HV. Specifically, at 10 wt. % Sn, the hardness was observed to be 250 HV which is quite near to reference alloy, i.e., 210 HV. Moreover, tensile strength (TS) of the alloys were calculated using hardness values since it was very difficult to prepare the test coupons using powders. The TS values were in the range of 975 to 1524 MPa at all concentrations of Sn. In particular, the TS at 10 wt. % Sn is 1149 MPa which is comparable to reference counterpart (1168 MPa). The corrosion rate of Titanium-Sn alloys (as of this study) and reference alloy, i.e., Ti6Al4V were also compared. Incorporation of Sn reduced the corrosion rate at large than that of reference counterpart. In particular, the trend was in decreasing order as Sn content increased from 5 to 20 wt. %. The minimum corrosion rate of 3.65 × 10−9 mm/year was noticed at 20 wt. % than that of 0.03 mm/year of reference alloy. This shows the excellent corrosion resistance upon addition of Sn at all concentrations. [ABSTRACT FROM AUTHOR]

The AlSi10Mg alloy is characterized by a high strength-to-weight ratio, good formability, and satisfying corrosion resistance; thus, it is very often used in automotive and aerospace applications. However, the main limitation of using this alloy is its low yield strength and ductility. The equal-channel angular pressing is a processing tool that allows one to obtain ultrafine-grained or nanomaterials, with exceptional mechanical and physical properties. The purpose of the paper was to analyze the influence of the ECAP process on the structure and hardness of the AlSi10Mg alloy, obtained by the selective laser melting process. Four types of samples were examined: as-fabricated, heat-treated, and subjected to one and two ECAP passes. The microstructure analysis was performed using light and electron microscope systems (scanning electron microscope and transmission electron microscope). To evaluate the effect of ECAP on the mechanical properties, hardness measurements were performed. We found that the samples that underwent the ECAP process were characterized by a higher hardness than the heat-treated sample. It was also found that the ECAP processing promoted the formation of structures with semicircular patterns and multiple melt pool boundaries with a mean grain size of 0.24 μm. [ABSTRACT FROM AUTHOR]

• The fatigue behavior of AA2014 alloy is investigated. • The fracture features of different regions were examined under Scanning electron Microscope. • The fatigue behavior of each sample is correlated with microstructural features. The present investigation studies the actual fatigue crack growth behavior of AA2014 alloy processed using multi-pass overlapping friction stir processing. The results revealed that friction stir processed samples sustained a large number of fatigue cycles than base metal due to the various microstructural aspects in the processed zone. The fractured surface of fatigue samples revealed the presence of ridges and plateaus in the Stage-I crack propagation region and dimples and striations in the Stage-II crack propagation region. [ABSTRACT FROM AUTHOR]

• A three-dimensional finite element model was established to calculate the temperature field. • Multi-layer multi-pass deposited samples of Invar alloy were fabricated by laser melting deposition. • The microstructure characteristics differ at different region of the deposited samples. • The grain size shows a dimension discrepancy at different region near the fusion line. Invar alloy has an important application in the manufacture of composite forming mould. The laser melting deposition (LMD) technology was utilized to fabricate multi-layer multi-pass deposited samples in this study. The effect of heat accumulation on the microstructure of deposition layer (DL) was investigated through experimental and simulation method. A finite element (FE) model was established to study the temperature field distribution in LMD process. Microstructure of DL was investigated by optical microscope (OM), scanning electron microscope (SEM), and energy dispersive spectrometer (EDS). The thermal cycle curves were extracted for analysis. The accumulation of heat during the deposition process would make the higher location DL reach a higher peak temperature. It could be seen from the observation of the transverse section of the deposited samples that the microstructure consisted of elongated cellular crystals and regular cellular crystals. At the bottom of the DL were columnar crystals grown epitaxially along the maximum temperature gradient and gradually transitioned to equiaxed crystals at the top of the DL. EDS detection results showed that there was no element aggregation phenomenon in the DL. The grains in the remelted zone were coarsened due to suffering a state of overheating. [ABSTRACT FROM AUTHOR]

In the present paper, the Mg-11Gd-2Y-1Zn alloys with different Al addition were fabricated by the gravity permanent mold method. The effect of Al content on microstructure evolution and mechanical properties of as-cast Mg-11Gd-2Y-1Zn alloy was studied by metallographic microscope, scanning electron microscope, XRD and tensile testing. The experimental results showed that the microstructure of as-cast Mg-11Gd-2Y-1Zn alloy consisted of α-Mg phase and island-shaped Mg3 (RE, Zn) phase. When Al element was added, Al2RE phase and lamellar Mg12REZn (LPSO) phase were formed in the Mg-11Gd-2Y-1Zn alloy. With increasing Al content, LPSO phase and Mg3 (RE, Zn) phase gradually decreased, while Al2RE phase gradually increased. There were only α-Mg and Al2RE phases in the Mg-11Gd-2Y-1Zn-5Al alloy. With the increase of Al content, the grain size decreased firstly and then increased. When the Al content was 1 wt.%, the grain size of the alloy was the minimum value (28.9 μm). The ultimate tensile strength and elongation increased firstly and then decreased with increasing Al addition. And the fracture mode changed from intergranular fracture to transgranular fracture with increasing addition. When Al addition was 1 wt.%, the maximum ultimate tensile strength reached 225.6 MPa, and the elongation was 7.8%. When the content of Al element was 3 wt.%, the maximum elongation reached 10.2% and the ultimate tensile strength was 207.7 MPa. [ABSTRACT FROM AUTHOR]

• The effects of Cu or Zn on the fluidity of A357 alloy were investigated. • With increase of Cu or Zn content, the fluidity of A357 alloy decreased. • With increase of Cu or Zn, the solidification temperature range increased. • The coarse grain is not the main reason for the fluidity to deteriorate. Excellent fluidity is an essential condition for Al-Si-Mg alloy (like A357) to make large thin-walled and complex structure castings, but t here is no research about the effects of Cu or Zn on the fluidity of Al-Si-Mg alloys. Under sand casting conditions, the effects of Cu or Zn on the fluidity of A357 were investigated through spiral fluidity resin sand molds, DSC, polarizing microscope and SEM. The results showed that with increase of Cu or Zn content, the solidification temperature range (T) of A357 alloy increased, and the fluidity decreased. With Cu or Zn addition, the grain size of A357 alloy increased, but the coarse grain is not the main reason for the fluidity to deteriorate. [ABSTRACT FROM AUTHOR]

Multicomponent aluminum-based alloys doped with chromium (Cr) and molybdenum (Mo), fabricated by spark plasma sintering (SPS), derived from a powder mixture prepared by mechanical alloying, were studied in this work. The morphology of the pristine and worn surfaces was analyzed using a scanning electron microscope equipped with an energy-dispersive X-ray spectroscopy system. The obtained alloys exhibited higher hardness (73 and 72) for the Al–Mo and Al–Cr alloys, respectively, compared to reference bronze. Besides improved hardness, SPS-sintered alloys also showed a lower value of the weight and linear wear and the highest score-resistance compared to bronze. The enhanced tribological behavior is related to the formation of secondary structures on the friction surfaces of rubbing pairs, which in turn reduce wear. For the first time, the present research has demonstrated the effectiveness of the addition of Mo and Cr for the fabrication of sintered multicomponent Al-based alloys with a tailored microstructure that induces the formation of secondary structures on the tribosurfaces due to the self-organization processes during friction. [ABSTRACT FROM AUTHOR]

Abstract  The influence of KCl(s) on the oxidation of Sanicro 28 (35Fe27Cr31Ni) austenitic stainless steel at 600 °C in 5% O2 + 40% H2O and in 5% O2 was investigated. The samples were coated with 0.1 mg/cm2 KCl(s) prior to exposure. The exposure time was 1, 24, 72 and 168 h. Uncoated samples were exposed for reference. The oxidized samples were analyzed by SEM/energy-dispersive X-ray (EDX), X-ray diffraction (XRD), and AES. The amount of chloride and chromate on the samples was analyzed quantitatively by ion chromatography after exposure. KCl(s) is very corrosive towards Sanicro 28. Corrosion is initiated by the formation of potassium chromate through the reaction of KCl(s) with the protective oxide, chloride leaving the sample in the form of HCl. Chromate formation is a sink for chromium in the oxide and leads to a deterioration of its protective properties. In the 5% O2 + 40% H2O environment, there is a stoichiometric relationship between the chromate formed and the chloride consumed. In dry O2 chromate formation is relatively slow, leaving more unreacted KCl(s) on the surface than in 5% O2 + 40% H2O. Once the protective, chromium-rich oxide has been depleted in chromium by chromate formation, the alloy becomes susceptible to direct attack by the remaining KCl(s). [ABSTRACT FROM AUTHOR]

The isothermal section of the Zn-Bi-Ni ternary system at 450 °C was determined experimentally using the equilibrated alloys approach. The specimens were investigated by means of optical microscopy, scanning electron microscopic/energy-dispersive spectrometric analysis and x-ray diffraction. Six three-phase regions exist in this isothermal section. The L-Bi phase is in equilibrium with all phases of Ni-Zn binary system except the α-Ni phase. Experimental results indicate that the third element, Zn or Bi, is almost insoluble in the Bi-Ni or Ni-Zn intermetallic compounds. [ABSTRACT FROM AUTHOR]

Directionally solidified Mn–20Cu–5Ni–2Fe alloy under different pulling rates were investigated by means of dynamic thermal mechanical analysis, optical microscope, X-ray diffraction and scanning electron microscope. It has been found that the favorable microstructure can be tuned through adopting appropriate pulling rate during the process of directionally solidification to approach ultra-high damping performance by enhancing the mobility of twin and dislocation. It is disclosed that the microstructure characterized by regular arranged dendrites with fluctuated composition, single parent phase with favorable orientation, large low-angle misorientation grains, and micron-scaled twins with the low angle misorientation boundaries, can leads to a substantially increase of twin boundary IF up to 2 times higher than the present ordinary manufacturing process. The result has important guiding significance for the research and preparation of ultra-high damping Mn–Cu based alloy. • The parent-phase twinning has been induced by antiferromagnetic transition. • RSLM effect of directionally solidified Mn–Cu alloy significantly improves the damping capacity. • (111) orientation enhances the mobility of twins and dislocations. • Internal friction (IF) is a function of the pulling rate and the secondary dendrite spacing. [ABSTRACT FROM AUTHOR]

Knowing of the wetting of filler alloy on substrate is significant for brazing. Here, the isothermal wetting behavior of Sn- x Cr alloys (x = 1, 2, 3, 4 and 5 wt%) on SiC substrates was studied by a modified sessile drop method in the temperature range of 1173 K–1323 K. The interfacial microstructures were characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD) and its evolution was analyzed thermodynamically. Also, the spreading kinetics is calculated and the formation of precursor film is discussed. The spreading of Sn melt on SiC consists of rapid-spreading and sluggish-spreading stages. A better wettability is obtained at higher Cr concentration and isothermal temperature. The direct reaction between Cr and SiC forming metallics Cr–C compounds (Cr 3 C 2 , Cr 7 C 3 and Cr 23 C 6) at the interface accounts for the improving wettability of Sn melt on SiC. More metallic Cr–C compound occupies a higher proportion of interfacial layer inducing a lower final contact angle. Temperature has a violent influence on the spreading kinetic constant K r. The spreading activity energy is calculated to be 312 kJ/mol. • Cr addition induces a good wetting of Sn–Cr alloy on SiC substrate. • Formation of Cr–C compounds at the interface improves the wettability of Sn–Cr alloys on SiC. • Spreading behavior of Sn–Cr alloy on SiC is controlled by the interface chemical reaction during isothermal wetting. [ABSTRACT FROM AUTHOR]

Room- and elevated-temperature wear tests were conducted using a pin-on-disk testing machine to study wear behavior of Mg97Zn1Y2 alloy and role of long-period-stacking-ordered (LPSO) structure phase in mild–severe wear transition (SWT). Variation of wear rate exhibited a three-stage characteristic with load at various test temperatures, i.e., a gradual increasing stage, a slightly higher plateau stage, and a rapid rising stage. The wear mechanisms in the three stages were identified using scanning electron microscope (SEM), from which the first stage was confirmed as mild wear, and the other two stages were verified as severe wear. The interdendritic LPSO structure phase was elongated into strips along the sliding direction with Mg matrix deformation in the subsurface, plate-like LPSO structure phase precipitated at elevated temperatures of 150 and 200 °C. The fiber enhancement effect and precipitation effect of LPSO structure phase resulted in a little difference in wear rate between the first and second stages, i.e., a masking effect on SWT. Microstructure and microhardness were examined in the subsurfaces, from which the mechanism for SWT was confirmed to be dynamic recrystallization (DRX) softening. There is an apparently linear correlation between the critical load for SWT and test temperature, indicating that SWT is governed by a common critical DRX temperature. [ABSTRACT FROM AUTHOR]

Abstract: Faceted nanoparticles of zinc oxide were successfully achieved via thermal annealing of hydrozincite (Zn5(CO3)2(OH)6) powder at different annealing temperatures, i.e. 300, 500 700 and 900°C in air for 2h using sol–gel method by refluxing for 6h at 70°C. Zinc acetate dihydrate (Zn(CH3COO)2·2H2O) was used as precursor with urea (NH2CONH2) for the synthesis of hydrozincite. The morphological observations by field emission scanning electron microscope indicated increase in particle size from 20 to 300nm with increase in the annealing temperatures. High resolution TEM and SAED measurement indicate the distance between two lattice fringes is ∼0.52nm corresponding to (0001) fringes. A standard peak of zinc oxide was observed at 457cm−1 from the FTIR analysis. Thermo gravimetric analysis (TGA) revealed that the primary weight loss starts at ∼130°C due to solvent evaporation and the secondary weight loss due to phase transition from hydrated zinc oxide to zinc oxide was observed at ∼290°C. [Copyright &y& Elsevier]

NiTi shape memory alloy (SMA) ingots were produced by vacuum induction melting/casting unit. The effect of microstructure on the hot (1000°C) and cold (room temperature) rolling workability of cast samples was investigated. Microstructure of the cast samples was related to the type of crucible which used for melting and the average vacuum pressure of VIM furnace. Optical microscope, scanning electron microscope (SEM), and energy dispersive technology (EDS) methods were used to inspect the origins of observed cracks after rolling processes. The results showed that the formation of both Ti4Ni2O and TiC impurities formed due to inappropriate melting conditions had detrimental effects on workability of the cast specimens and caused failure in the hot and cold rolled alloys. [ABSTRACT FROM AUTHOR]

Abstract: Ag/ZnO contact material was prepared by gas atomization internal oxidation forging technology (AIOF technology). The granularity, morphology and component of gas atomized Ag/Zn alloy powder were studied; the phase constitution, microstructure and physical performance were analyzed by X-ray diffraction (XRD), optical microscope (OM) and scanning electron microscope (SEM), respectively. Furthermore, the oxidation mechanism of Ag-based alloy was also discussed. The results showed that 82% gas atomized Ag/Zn alloy powders were less than 125μm in diameter of irregular shape. The microstructure was homogeneous with electrical contact resistance equal to 2.10μΩcm and of 98% relative density and hardness of 102.8HV. The performance was much better than that prepared by conventional powder metallurgy method. The oxidation of Ag-based alloy was considered to be controlled by oxygen diffusion. [Copyright &y& Elsevier]

In this technical paper, the microstructure, hardness, tensile deformation and final fracture behaviour of an emerging titanium alloy for performance-critical applications are presented and discussed. Both longitudinal and transverse test specimens were prepared from the as-provided sheet stock of the alloy and deformed in uniaxial tension. The yield strength and tensile strength of the alloy sheet in the transverse orientation was higher than the longitudinal orientation. The ductility of the test specimens, quantified in terms of reduction-in-cross-sectional area, was higher for the transverse specimen when compared to the longitudinal counterpart. The elongation-to-failure of the test specimens was identical in the two orientations of the sheet stock. The tensile fracture behaviour of the alloy was quantified by careful examination of the fracture surfaces in a scanning electron microscope. The intrinsic fracture features on the tensile fracture surface were discussed taking into consideration the nature of loading and contribution from intrinsic micro-structural features. [ABSTRACT FROM AUTHOR]

Abstract: The electropolishing behavior of the Inconel 718 alloy was studied by using rotating disc electrode (RDE) in the HClO4–CH3COOH mixed acids with different HClO4-concentrations. After electropolishing, surface morphologies of RDE specimens were examined with surface profiler, atomic force microscope and scanning electron microscope. According to the surface morphologies observed, three types of anodic dissolution behavior can be characterized in relation to the HClO4-content in mixed acids; namely, leveling without brightening of the surface in the mixed acids with 10 and 20vol% HClO4, leveling and brightening of the surface in the mixed acids with 30 and 40vol% HClO4, and a matt and gray surface in the mixed acids with 50vol% or more HClO4. Anodic dissolution in the first and second dissolution types follows a mass-transfer controlled mechanism, in which a linear relationship between the reciprocal of limiting-current density and the reciprocal of square root of rotating speed of RDE specimen can be detected. Owing to precipitation of salt film on the polished surface of the Inconel 718 material, saturated dissolved metallic ions could be the chemical species for the mass-controlled mechanism. The salt film, in addition, could enhance the corrosion resistance of the Inconel 718 alloy. [Copyright &y& Elsevier]