Microhardness Of Alloy Research Articles

Effect of Sn Addition on Phase Transformation Behavior of Equiatomic Ni-Ti Shape Memory Alloy

Sn effect on the phase transformation behavior, microstructure, and micro hardness of equiatomic Ni-Ti shape memory alloy was studied. NiTi and NiTiSn alloys were produced using vacuum induction melting process with alloys composition (50% at. Ni, 50% at.Ti) and (Ni 48% at., Ti 50% at., Sn 2% at.). The characteristics of both alloys were investigated by utilizing Differential Scanning Calorimetry, X- ray Diffraction Analysis, Scanning Electron Microscope, optical microscope and vicker's micro hardness test. The results showed that adding Sn element leads to decrease the phase transformation temperatures evidently. Both alloy samples contain NiTi matrix phase and Ti2Ni secondary phase, but the Ti2Ni phase content decreases with Sn addition and this is one of the reasons that leads to decrease the micro hardness of alloy with adding Sn element in a noticeable manner. The micro hardness decreases from 238.74 for NiTi equiatomic alloy to 202 for NiTiSn alloy after heat treatment.

STUDY OF Zn–Co ALLOY COATINGS MODIFIED BY NANO- TiO2 PARTICLES INCORPORATION

The purpose of this paper is to investigate the effect of TiO2 nanoparticles contents on structural properties, microhardness and corrosion resistance of Zn-Co alloy coating and ZnCo-TiO2 composite coatings is electrodeposited on steel substrate in the acid sulfate bath, The smaller grain size of the composite coatings is observed in the presence of TiO2 and it is confirmed by the images of scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The corrosion performance of coating in the 3 % NaCl as a corrosive solution is investigated by potentiodynamic polarization and electrochemical impedance spectroscopy EIS methods. It is found that the incorporation of nanoparticules in Zn–Co alloy coating have better corrosion resistance and the values of Rct and Zw increase, while the values of Cdl decrease with the increasing of nanoparticules

Effect of 4 Wt% Magnesium on The Micro-hardness Of Aluminum Alloy Synthesized by Mechanical Milling

Effect of 4 Wt% Magnesium on The Micro-hardness Of Aluminum Alloy Synthesized by Mechanical Milling

Effect of Heat Treatment on Structure and Microhardness of Ti50Pd40Ni10 Alloy with High-Temperature Shape Memory Effect Studied on Rod-Shaped Blank

Integrated studies of the structure and microhardness of Ti50Pd40Ni10 alloy (at %) with a high-temperature shape memory effect have been carried out. The studies have been performed on alloy specimens cut from a rod 5.86 mm in diameter in the initial state and after various heat-treatment conditions. Data on the elemental and phase compositions, microstructure, grain size, and microhardness have been obtained. It has been suggested from the results of the studies of local phase composition of the alloy that ductility characteristics and, consequently, the shape memory effect of the specimens fabricated from a rod would be less than those of the specimens fabricated from a strip. It has been determined from the results of metallographic studies that the lowest microhardness of the rod alloy is intrinsic after annealing in vacuum at 850°C for 1 h and cooling with the furnace. Then, it could be suggested that residual strain and shape memory effect would be the greatest under these conditions. The results of structural studies of the Ti50Pd40Ni10 alloy (at %) will be considered by the authors in the development of various safety devices in nuclear power plants.

Investigation on mechanical properties of Al6061 alloy – Multiwall carbon nanotubes reinforced composites by powder metallurgy route

Al6061 alloy reinforced multiwall carbon nanotubes composites is manufactured by powder metallurgy process. Microstructure of samples is investigated using scanning electron microscope to check the distribution of carbon nanotubes in aluminium alloy. Micro hardness, impact strength and ultimate tensile strength of Al6061 alloy and Al6061 alloy - multiwall carbon nano tubes composites are examined. Micrograph of composites shows better dispersion of multiwall carbon nanotubes in Al6061 alloy. Addition of multiwall carbon nanotubes improved the hardness, impact strength and ultimate tensile strength of matrix. Hardness of Al6061 increased up to 18.6% by reinforcing 1.5 wt% of multiwall carbon nanotubes in Al6061 alloy. Impact strength and ultimate tensile strength increased up to 66.6and 11.93% respectively by adding 1.5 wt% of reinforcements in Al6061 alloy. 1.5 wt% of multiwall carbon nanotubes in aluminium 6061 alloy offered better mechanical properties compared to Al6061 alloy and 1.5 wt% reinforced Al6061 composites.

Effects of Fe and Mn on Microstructure and Microhardness of Titanium Alloys

Titanium is one of the most appreciated biocompatible materials, as it possesses both good mechanical characteristics but also high corrosion resistance in contact with biological environments. Initially, Ti-6Al-4V trade mark was used for the manufacture of implantable medical devices, being usually selected for making aerospace structures. Over time, it has been found that aluminum and vanadium are not elements with acceptable biocompatibility, metallic ions being found either dissolved or accumulated in certain areas adjacent to the implants. Therefore, the development of titanium alloys dedicated to biomedical applications is still highly required. The effects of chemical elements (Al, Fe and Mn) on the microstructure and microhardness of titanium alloys for medical applications are analyzed in the paper. The experimental alloys were obtained by melting of raw materials in an argon inert atmosphere of the VAR equipment, using high purity metallic elements. Has been developed Ti-base alloys that contain different concentration of 11 to 18 wt. % Al, 2 to 7wt. % Fe and 6 wt. % Mn for highlighting the effects of these elements on the micro-structure and microhardness of titanium alloys. SEM and EDAX analysis revealed the microstructure and microhardness changes occurred by using of alpha stabilizing elements (Al) or beta stabilizers (Fe, Mn).

The effect of homogenizing annealing on the microstructure and microhardness of Ti-20Nb-(7.5-10)Ta alloys (at.%)

The microstructure and microhardness of Ti-20Nb-7.5Ta and Ti-20Nb-10Ta alloys (at. %) after smelting and after homogenizing annealing at 900°C and 950°C for 12 hours were studied. It was shown that, after smelting, the alloys have a dendritic structure, and after annealing, they have a polycrystalline structure with equiaxed grains. It is also shown that annealing leads to an increase in the microhardness of alloys.

Study of α”-Martensitic Transformation in Ti35NbxSn Alloys Subjected to Cryogenic Heat Treatment

TiNbSn alloys have been extensively researched due to several properties they exhibit, including high mechanical strength, low elastic modulus, superelasticity, shape memory effect, biocompatibility. The present study evaluated the cryogenic heat treatment in the Ti35NbxSn alloys (x = 0.0; 2.5; 5.0; 7.5). The alloys were arc melted, cold formed and quenched in both water and liquid nitrogen at-198° C. The Ti35Nb2.5Sn alloy was also aged after exposed to both quenching medium. Microstructure and microhardness analyses were performed. Cryogenic treatment was not enough for transformation of primary β phase into martensitic α” in alloys containing 5 and 7.5% Sn. Cryogenic treatment provided β to α” transformation in alloys containing 0 and 2.5% Sn. The Sn-free alloy was more likely to α" transformation in both quenching medium. The alloys microhardness increased with decrease of both quenching temperature and Sn content. The increase of α" is also related to the increase of the alloy microhardness after aging.

Features of the structure and properties formation of AMG6 alloy under the equal channel angular pressing

The results of experimental studies of changes in the structure, microhardness, and wear resistance of the AMG6 aluminum alloy during equal channel angular pressing (ECAP) are presented in this work. The evolution of the fine structure and the formation of secondary phases in the AMG6 alloy during ECAP were studied. The dark-field image of the structure of the AMg6 alloy in the matrix reflex showed the splitting of the material into small disoriented fragments of about 0.5 μm in size with a small-angle disorientation boundary (about 2–5°). Optimal method and modes of ECAP of the AMG6 aluminum alloy were selected of the bases of experimental research, which make it possible to obtain a workpiece with enhanced tribological and mechanical characteristics. It was established that the most intensive grinding of the grain structure in the AMG6 alloy occurs at ECAP-12 at a channel angle intersection of 120°. It is shown that with a decrease in grain size, the microhardness of the alloy AMG6 after ECAP increases by 4 times, compared with the initial state.The results of the test samples for abrasive wear showed a decrease in mass loss after 12 passes of ECAP, which indicates an increase in the wear resistance of the alloy AMG6 by 13–14 %, compared with the initial state.

Synthesis of Ti-Al intermetallic coatings via electrospark deposition in a mixture of Ti and Al granules technique

In this paper, the results of studies of the formation of Ti-Al intermetallic coatings on a Ti6Al4V alloy by the electric spark deposition method in a mixture of titanium and aluminum granules are presented. Five mixtures of granules with an aluminum concentration of 24 to 88 at.% were prepared. As the concentration of aluminum in the mixture of granules increased, the phase composition of the corresponding coatings changed from αTi and titanium rich aluminides to aluminum aluminides rich and Al. According to EDS analysis, with an increase of the aluminum content in the mixture of granules from 24 to 88 at.% its concentration on the surface of the coatings increased from 19 to 68 at.%. The main mechanism of Ti-Al coatings formation at electrospark granule deposition is convective mixing of melted materials of granules and substrate. Potentiodynamic polarization tests in a 3.5% NaCl solution showed that coatings can improve the corrosion resistance of the Ti6Al4V alloy. A high-temperature corrosion test for 100 h at 900 °C showed that coated samples were oxidized 1.1–3.4 times less than initial Ti6Al4V substrate. The best oxidation resistance properties showed the coating with the highest aluminum content. Electric spark granule deposition increase microhardness of Ti6Al4V alloy up to 6.4–9.4 GPa. The wear resistance of the coatings at dry sliding with 10 and 25 N loads was 4–27 and 6–36 times higher, respectively, than wear resistance of the initial alloy. The wear rate of coatings decreased with increasing titanium concentration.

Preparation and characterization of equiatomic NiTi shape memory alloy

The present study investigated the vacuum induction melting of equiatomic NiTi (Ni 50 at. %, Ti 50at. %) shape memory alloy using graphite crucible. The cast alloy heat-treated at 865° C for 15 mints, followed by quenching the sample in icy water. The microstructure and micro hardness of alloy were investigated before and after heat treatment by using an optical microscope and Vickers micro hardness tester. Transformation temperatures upon heating/cooling were investigated by using differential scanning calorimeter (DSC). Scanning electron microscope (SEM) supported with energy dispersive X-ray (EDX) and X-ray diffraction analysis (XRD) were carried out to investigate the chemical composition and the phases present in the alloy after heat treatment. The results show that the vacuum induction melting process in a graphite crucible provides binary NiTi shape memory alloys with good chemical homogeneity. The microstructure becomes more homogenous and the Vickers’s micro hardness increases from 186.06 to 238.74 after heat treatment with highly controlling on the composition of the alloy. The DSC curve shows that the R- phase exists upon the heating and cooling process. In addition the precipitate phase Ti2Ni was also exist.

Microstructure and mechanical properties of Sn-9Zn-xAl and Sn-9Zn-xCu lead-free solder alloys

Abstract This study investigates microstructures and mechanical properties of the alloys obtained by adding Cu (0.7 % and 0.9 %) and Al (0.7 % and 0.9 %) to lead-free Sn-9Zn eutectic soldering alloy produced by investment casting method. The results show that Cu5Zn8 phase has formed in the structure of Cu added alloys and the Al2O3 phase has formed due to addition of Al. It was found that small and round-shaped Al2O3 phase increased the tensile strength of the new alloy compared to the eutectic alloy. In addition, it was observed that the microhardness of Cu added alloys was lower than that of Sn-9Zn eutectic alloy, but the microhardness of alloys containing Al was higher compared to the other eutectic Sn-9Zn alloy.

Characterization the wear behavior of Al-Ti alloy having different Ti ratios prepared by powder metallurgy

In this study, the Al-Ti alloy was fabricated by powder metallurgy method using three different Ti ratios (10wt%; 15wt%; and 20wt%Ti); and the wear behavior of these three alloys was investigated. The mixtures of powders were compacted at 146 MPa and sintered for 5 hours at 550- ˚C under vacuumed atmosphere. The samples were characterized using X-Ray Diffraction test (XRD), Scanning Electron Microscope test (SEM), microhardness and density tests. The tests of wear were achieved by employing a pin on disk machine under constant normal load 15N for four different sliding times 5, 10, 15, and 20 minutes. The results illustrate that the density and microhardness of Al-Ti alloy were increased as the Ti content increased. Also, it was observed that Al-Ti alloy with 20wt%Ti had the highest wear resistance and lowest weight loss.

Growth kinetics, microhardness and microstructure evolution of undercooled FeCoNiCuSn high entropy alloy

Multi-principle element alloy FeCoNiCu with varying Sn addition was undercooled using the meltfluxing technique to illustrate the dependence of growth kinetics on Sn addition. The alloy FeCoNiCuSn0.5 shows morphological variation in the microstructure from dendritic to equiaxed grain morphology with the increase in undercooling. The alloy FeCoNiCuSn5 shows dendrite morphology with undercooling. The dendritic growth velocity was sluggish with solute addition,i.e., at an undercooling of 200 K, the growth velocity decreased from ~25 m/s to 6 m/s while varying Sn concentration from 0.5 to 5 at % suggesting solute drag effect. The microhardness improvement could be correlated to the microstructure refinement achieved during undercooling.

Effect of (Pr + Ce) addition and T6 heat treatment on microhardness and corrosion of AlSi5Cu1Mg alloy

The effects of T6 heat treatment and 0.6 wt% (Pr + Ce) addition on microstructure, microhardness, and corrosion of AlSi5Cu1Mg alloy were investigated. Optical microscopy and scanning electron microscopy revealed that the T6 heat treatment and the addition of 0.6 wt% (Pr + Ce) effectively refined the α-Al and eutectic Si phases, which were uniformly distributed with Al2Cu phase in the alloy. Microhardness, weight loss, hydrogen evolution, Tafel polarization, and EIS tests showed that the combination of T6 heat treatment and 0.6 wt% (Pr + Ce) addition resulted in the best corrosion resistance and microhardness of the alloy. The microhardness of the AlSi5Cu1Mg+0.6 wt% (Pr + Ce)/T6 (115 HV) was 27.8% higher than that of the matrix (90 HV). At the same time, the corrosion current density of the alloy also reached the minimum value (38.4 μA cm−2). The T6 heat treatment and the addition of (Pr + Ce) can significantly decrease the average grain size, change the redistribution of the precipitated Al2Cu phase, refine the Si phase, and increase the pitting formation position, thus reducing the sensitivity of exfoliation corrosion.

Structure and Phase Composition of a W-Ta-Mo-Nb-V-Cr-Zr-Ti Alloy Obtained by Ball Milling and Spark Plasma Sintering.

In this paper, the structural characteristics of a W-Ta-Mo-Nb-V-Cr-Zr-Ti non-equiatomic refractory metal alloy obtained by spark plasma sintering (SPS) of a high-energy ball-milled powder mixture are reported. High-energy ball milling resulted in the formation of particle agglomerates ranging from several tens to several hundreds of micrometers. These agglomerates were composed of micrometer and submicrometer particles. It was found that, during ball milling, a solid solution of A2 structure formed. The grains of the sintered material ranged from fractions of a micrometer to several micrometers. During SPS, the phase transformations in the alloy led to the formation of a Laves phase of C15 structure and ZrO and ZrO2 nanoparticles. The microhardness of the ball-milled alloy and sintered material was found to be 9.28 GPa ± 1.31 GPa and 8.95 GPa ± 0.42 GPa, respectively. The influence of the processing conditions on the structure, phase composition, and microhardness of the alloy is discussed.

Influence of decomposition of oversatured liquid solutions on the structure and microhardness of quickly curing alloys of the Pb–Sn system

The results of studies of the structure and microhardness of foil alloys of the lead–tin system obtained by high-speed cooling from the liquid phase are presented. The foil sample had the following dimensions: length – up to 10 cm, width – up to 1 cm, and thickness – 30–80 microns. Melt cooling rate was not less than 105 K/s. A rapidly cooled foil is chara cterized by a dispersed structure. The size of the discharge of tin and lead does not exceed 5 μm. The specific surface of the interfacial boundaries achieve 1.7 μm–1. Due to supercooling, a microcrystalline structure forms in the foil. The average lengths of chords of random secants on lead and tin grain sections in the Pb–73 at.% Sn alloy foil are 0.8 and 1.8 μm respectively. The texture of (111) lead and (100) tin is formed in the foil of alloys of the lead – tin system under certain conditions. The formation of the structure of lead alloys containing from 20 to 95 at.% tin is due to the occurrence of spinodal decomposition of a supersaturated liquid solution, and, in other alloys, due to decay by the mechanism of formation and growth of nuclei of crystalline phases. The stratification of the liquid solution leads to the formation of areas enriched in lead and tin, which contribute to the formation of crystallization centers that are equally distributed in the volume of the foil. The microhardness of the foil alloys, whose compositions are close to eutectic, is less than the microhardness of massive alloys of the same composition, which is associated with the softening effect of grain boundaries and interphase boundaries. Exposure of these alloys at room temperature causes an increase in microhardness due to a decrease in slippage at the boundaries. The decomposition of supersaturated solid solutions of Pb–5 at.% Sn and Sn–1 at.% Pb alloys leads to a decrease in microhardness due to the weakening of the effect of the solid solution hardening mechanism. The results of the study can be used to create fusible solders, bearing alloys, alloys for cable sheaths with improved physicochemical properties.

Effect of interlamellar spacing on microhardness and yield strength of annealed Ti6AlCo alloys made by powder sintering method

The compressive yield strength and microhardness of the Ti6AlCo alloys have been studied as a function of interlamellar spacing. Also a correlation between strength and microhardness was established. It was observed that microhardness of the alloy is increasing with decrease in interlamellar spacing (ILS) of the lamellae of eutectoid phase colony. Further, it was observed that increase in Co concentration in the Ti6Al alloys decreased the ILS. The strength of the material was also found to have correlation with microhardness. The values of constant correlating microhardness and compressive yield strength were obtained and compared with the existed value and found to be in good agreement with each other.

Microstructure and microhardness of the Al-10Mg alloy processed by the mechanical alloying technique

In this work, the Al-10Mg nanostructured alloy was synthesized by high-energy mechanical milling. Subsequently, the powders consolidated under a uniaxial pressing in the air. The as milled powders were analyzed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). SEM and XRD also characterized the sintered samples. Vickers microhardness of sintered Al-10Mg alloy was measured. SEM, XRD, and TEM characterizations show that the Al-10Mg alloy was synthesized after 10 h milling. The X-ray powder analysis of the structural parameters showed the increment with the time of the lattice parameter, strain as well as the solubility of Mg in Al. Besides, XRD and TEM studies showed that the crystallite size was reaching an average value of 19 nm after 10 h milling. XRD patterns of the all sintered specimens show the formation of the MgAl2O4 spinel phase. After powders compaction, the specimen sintered at 420?C for 2 h shows microhardness of 125 HV.

Laser Shock Peening on Al-Si10-Mg Produced by DMLS Technique

Abstract In Additive manufacturing, direct metal laser sintering (DMLS) is a technique for manufacturing of Metal bases 3D printing. Finely pulverized metal is melted using a high-energy fibre laser, by Island principle strategy produces mechanically and thermally stable metallic components with reduced thermal gradients, stresses & at high precision. Al-Si10-Mg alloys are being used in aircraft and automobile parts. However, this component is susceptible to lack of hardness and corrosion resistance when exposed to higher load bearing operations and industrial environments. The laser shot peening of Al-Si10-Mg prepared by DMLS process was found to enhance micro hardness of aluminium alloy. The formation of closed packed and oriented micro grains of metal atoms at interstitial layers have been ascertained from SEM and TEM studies. AFM measurements revealed that formation of micro rough surfaces and also dislocation of new grains have significantly contributed to enhancement of mechanical properties of Al-Si10-Mg alloys