Properties Of Alloys Research Articles

Mechanical Properties, Microstructure, Degradation Behavior, and Biocompatibility of Zn-0.5Ti-0.5Fe and Zn-0.5Ti-0.5Mg Guided Bone Regeneration Barrier Membranes Prepared Using a Powder Metallurgy Method.

Pure zinc exhibits low mechanical properties, making it unsuitable for use in guided bone regeneration (GBR) membranes. The present study focused on the preparation of Zn alloy GBR films using powder metallurgy, resulting in Zn-0.5Ti-0.5Fe and Zn-0.5Ti-0.5Mg alloy GBR films. The tensile strength of the pure Zn GBR film measured 85.9 MPa, while an elongation at break was 13.5%. In contrast, Zn-0.5Ti-0.5Fe and Zn-0.5Ti-0.5Mg alloy GBR films demonstrated significantly higher tensile strengths of 145.3 and 164.4 MPa, respectively, whereas elongations at break were 30.2% and 19.3%. The addition of Ti, Fe, and Mg substantially enhanced the mechanical properties of the zinc alloys. Corrosion analysis revealed that Zn-0.5Ti-0.5Fe and Zn-0.5Ti-0.5Mg alloy GBR membranes exhibited corrosion potentials of -1.298 and -1.316 V, respectively, with corresponding corrosion current densities of 12.11 and 13.32 μA/cm2. These values were translated to corrosion rates of 0.181 and 0.199 mm/year, indicating faster corrosion rates compared to pure Zn GBR membranes, which displayed a corrosion rate of 0.108 mm/year. Notably, both Zn-based alloy GBR membranes demonstrated excellent cytocompatibility, with a cytotoxicity rating of 0-1 in 25% leachate. Additionally, these membranes exhibited favorable osteogenic ability, as evidenced by the quantitative bone volume/tissue volume ratios (BV/TV) of new bone formation, which reached 30.3 ± 1.4% and 65.5 ± 1.8% for the Zn-0.5Ti-0.5Fe and Zn-0.5Ti-0.5Mg alloy GBR membranes, respectively, after 12 weeks of implantation. These results highlighted the significant potential for facilitating new bone growth. The proposed Zn-0.5Ti-0.5Fe and Zn-0.5Ti-0.5Mg alloy GBR membranes showed promise as viable biodegradable materials for future clinical studies.

Effect of quenching and solubilization temperature on thermal, electrical, mechanical, and magnetic properties of a Heusler CuAlMnTiB alloy

We report a systematic investigation of the effect of quenching and solubilization temperature on the thermal, electrical, mechanical, and magnetic properties of the Heusler alloy CuAlMnTiB. The experimental procedure and the results obtained demonstrated that the tempering process can effectively adjust the physical properties of the CuAlMnTiB alloy. This treatment led to an increase in electrical resistivity, which went from 2.34×10−7Ω∙m in the raw melt sample (TBF) to 4.49×10−7Ω∙m in the sample quenching at 850 ºC (T850), in addition to an increase in the Curie temperature, from 297.5 ºC (TBF) to 305.85 ºC (T850). A decrease in remanent magnetization from 2.74 emu/g (TBF) to 0.31 emu/g (T850) and in the coercive field, which reduced from 54.15 Oe in the TBF to 4.55 Oe in the T850, was also observed. This makes tempering a viable alternative to adapt these properties to various technological applications, without requiring changes in the alloy composition. Here we were able to reach structural and magnetic properties compatible with those reported in the literature for CuMnAl alloys of different compositions.

Optimization of high-temperature mechanical properties of aluminum alloys through exclusive precipitation of T-phase

An aluminum alloy with an actual composition of Al - 5.4 wt%Cu- 1 wt%Mn was cast and subjected to solution heat treatment for 1 h, 2 h, 4 h, 8 h, and 16 h to make the T-phase the sole strengthening phase. The microstructural evolution of the samples, especially the T-phase microstructure, was studied using transmission electron microscope (TEM) and scanning electron microscope (SEM) with electron backscatter diffraction (EBSD) attachment. The ImageJ software was utilized to statistically analyze T-phase content. Tensile tests were conducted to obtain mechanical property data, and high-temperature tensile tests were performed at 200 °C, 300 °C, and 400 °C to assess the high-temperature performance. Subsequently, the strengthening effect of the T-phase on the room-temperature and high-temperature mechanical properties of the aluminum alloy was quantitatively evaluated. The sample subjected to an 8 h solution treatment exhibited optimal strength and toughness. The yield strength was 147 MPa, and the tensile strength was 300 MPa. The yield strength contributed by the T-phase was 73 MPa. The tensile strength of the sample at 400 °C remained at 91 MPa. The T-phase contributes significantly to the mechanical properties of the aluminum alloy both at room temperature and at high temperatures.

Preparation of ultrafine WC-V8C7-Cr3C2-co cemented carbides by spark plasma sintering in-situ synthesis of composite grain growth inhibitors

The growing high-precision manufacturing industry is increasing the demand for cemented carbide which has fine grain size and excellent machinability. In this research, ultrafine cemented carbide was successfully prepared by the method of in-situ synthesis using spark plasma sintering as densification method, V, Cr, WC and carbon black as raw materials. The formation mechanism of in-situ preparation of grain growth inhibitors (GGIs) and its influence on the properties of alloys were investigated. An excellent mechanical property (HV 2254 kgf/mm2, KIC 9.20 MPa·m1/2) and uniform microstructure of the alloys (0.8 wt% V8C7–0.8 wt% Cr3C2) prepared under 1350 °C, 6 min, 25 MPa were demonstrated by the results. The WC grain growth was significantly inhibited (about 200 nm). The in-situ synthesized GGIs significantly inhibited grain coarsening by interfering with the dissolution-precipitation process of WC during liquid-phase sintering. The combination of SPS and in-situ synthesized GGIs offers a novel approach to exploration of the preparation of high-performance ultrafine or nanocrystalline cemented carbides.

Effect of Nb and Ti additions on microstructure, hardness and wear properties of AlCoCrFeNi high-entropy alloy

The use of Nb and Ti in the development of high-performance alloys is strategically important for technological advancement. The effect of Nb and Ti additions on the microstructure, hardness and tribological properties of the High Entropy Alloy (HEA) AlCoCrFeNi was evaluated. The addition of 0.6mol of Nb led to the formation of Laves phase, resulting in a B2/Laves type hypoeutectic microstructure. Conversely, increasing Ti concentration led to the formation of a dendritic microstructure, with interdendritic region composed of Cr-rich BCC-A2 and Fe-Ti rich Laves phase. The average hardness values obtained were 790 HV, 597 HV and 731 HV for AlCoCrFeNiNb0.6, AlCoCrFeNiTi0.5 and AlCoCrFeNiTi1.2 HEAs, respectively. The high hardness was attributed to the formation of the Laves phase and Cr-rich phases, in addition to solid solution hardening, as confirmed by the increase in the lattice parameter calculated by Rietveld refinement method for both B2 and BCC-A2 phases. While the three compositions exhibited comparable friction coefficient, the alloy containing Nb showed superior wear behavior. This was evidenced by the lower volume of material loss and the lower wear rate, which can be attributed to the fine and homogeneous hypoeutectic microstructure observed in the ingot’s cross section. The wear mechanisms were studied, characteristics features of abrasion and adhesion wear were observed.

Formation of seaweed morphology and enhancing mechanical properties of an A356 alloy by directional solidification

In the present work, regular dendrite and seaweed pattern are produced by controlling the crystal orientation during directional solidification of an A356 aluminium alloy. These morphologies and growth orientation were investigated by electron backscatter diffraction (EBSD), and the results showed that the seaweed pattern mainly prevailed under the (100)[011] orientation. At the same time, the effects of seaweed pattern in the properties of A356 alloy were analysed by room temperature tensile test. It was found that the elongation and toughness of the samples reached 20% and 36J/m3, respectively, for the seaweed; 13% and 24J/m3, respectively, for the regular dendrites; and 8% and 14J/m3, respectively, for the cast ingot. Compared with the regular dendrite samples, the seaweed pattern obtained relatively excellent elongation and toughness. By using scanning electron microscopy (SEM), it is found that the distribution of eutectic silicon particles in seaweed morphology sample is more refined and uniform, which is the main reason for these enhancements.

Structure analysis (XRD and Neutrons) and hydrogen storage properties of Hf1-xTixNbVZr BCC high entropy alloys

The hydrogen storage properties of Hf1-xTixNbVZr high entropy alloys (HEAs) synthesized by arc melting have been investigated. The first hydrogenation of the alloys was performed at room temperature under 20 bars of hydrogen pressure. Results show an increase in gravimetric hydrogen content with Ti substitutions. Upon hydrogenation, the multiphase alloys (x = 0 and x = 0.25) exhibit a combination of faces-centred-cubic (FCC) hydride and C15 Laves phases, while single-phase alloys (x = 0.5, 0.75, and 1) display FCC structures.The crystal structure evolution during dehydrogenation of HfNbVZr (x = 0) and TiNbVZr (x = 1) HEAs was examined using in-situ neutron diffraction. The analysis demonstrates temperature-dependent desorption behaviour, with HfNbVZr displaying lower desorption temperatures compared to TiNbVZr. Additionally, in-situ neutron diffraction experiments during deuterium desorption indicate a two-step phase transition from FCC dihydride to BCT monohydride, followed by a transition to BCC.

Large coercivity and enhanced magnetization in La-substituted Sm6Mn23 alloys

The magnetic properties of Sm6Mn23-based alloys are still not fully understood for their high complexity in magnetic and crystallographic structures. This work presents studies of the structure and magnetic properties of Sm6Mn23 and Sm5LaMn23 alloys. The results show that both the binary and La-substituted ternary alloys crystallize in a cubic Th6Mn23 type structure (Fm-3m) with trace amount of Mn impurities. The lattice parameter of Sm5LaMn23 is slightly larger than that of Sm6Mn23. The Curie temperature of Sm5LaMn23 is ∼403 K, which is lower than that of Sm6Mn23. A field-dependent magnetic transition was observed in Sm5LaMn23, which shows a decreasing temperature at which Sm5LaMn23 exhibiting maximal magnetization with increasing field, indicating a suppression of the antiferromagnetic coupling of the rare earth and Mn moments under applied field. Large coercivities up to 0.74 T and 1.2 T are observed in Sm5LaMn23 bulk alloys and powders, respectively. The saturate magnetization, the remanent magnetization, and the coercivity of Sm5LaMn23 at 5 K are much higher than that of Sm6Mn23. The ball-milled Sm5LaMn23 powders exhibit significantly enhanced coercivity and magnetization. The refinement of the grain size during ball-milling results in the enhanced coercivity. The magnetic purification of the powders and possible local ferromagnetic configuration of the surface Mn atoms may result in the enhanced magnetization.

Research on tribological properties of new Ni-based single crystal alloy containing Re

Abstract The particles in high-temperature and high-speed airflow in the battlefield environment will form sliding friction and wear on the aeroengine turbine blades, thus reducing the service performance of the blades. However, few studies has been reported on the tribological properties of Ni-based single crystal alloy. Accordingly, the tribological properties of Ni-based single crystal alloys with different contents of Re (0 wt%, 1.5 wt%, 2.5 wt%, 3.5 wt%, 4.5 wt% and 5.5 wt%) are investigated by tribological experiments and molecular dynamics simulations in this paper. The results of tribological experiments show that Ni-based single crystal alloy without Re exhibits the characteristics of abrasive wear and adhesive wear, while the wear state is significantly improved after adding Re element. In particular, the worn surface of Ni-based single crystal alloy containing 5.5% Re (NSCA5) is the smoothest and only a few minor defects are observed. In addition, the micro-tribological characteristics of Ni-based single crystal alloy are analyzed by molecular dynamics simulations, the results show that Re atoms can inhibit the dislocation movement and reduce the system potential energy, which enhance the stability and hardness of Ni-based single crystal alloy, thereby the wear resistance of the material are improved.

Ameliorating the microstructure and properties of a Cu[sbnd]Cr alloy by introducing a high-temperature short-time treatment into the thermo-mechanical process

The optimization of process is essential for improving the overall properties of high-strength and high-conductivity Cu alloys. This study introduces a high-temperature short-time treatment (HTSTT, 850 °C/5 min) into the thermo-mechanical process of a CuCr alloy. Following the process of “solid solution - cold rolling - HTSTT - cold rolling - aging”, the tensile strength of the alloy increases from 450 MPa to 508 MPa, with the electrical conductivity increasing from 82.2 %IACS to 86.4 %IACS when compared to the conventional process of “solid solution - cold rolling - aging” under the same total deformation condition. The reasons for the improvement in the comprehensive properties of the alloy after introducing HTSTT are analyzed through microstructural characterization. The results indicate that the HTSTT promotes the occurrence of recrystallization, leading to grain refinement, which results in smaller grain sizes during subsequent processing. Additionally, the introduction of HTSTT changes the main texture of the alloy from 〈100〉//X to 〈111〉//X during the process, which is beneficial to enhancing the alloy's strength and electrical conductivity. More importantly, the HTSTT facilitates the precipitation of solute Cr atoms, leading to the formation of a significant quantity of nanoscale Cr particles, most of which are spherical with an average size of 27 nm. During the subsequent cold rolling process, these Cr particles effectively pin dislocations and promote their proliferation, leading to the precipitation of a large number of smaller Cr particles during the aging process, with an average size of 4.8 nm. These finer Cr particles are crucial for precipitation strengthening. This paper offers valuable insights into the microstructural optimization and performance enhancement of high-strength and high-conductivity Cu alloys.

Microstructure evolution by thermomechanical processing and high-temperature mechanical properties of HCP-high entropy alloys (HEAs)

The solid solution strengthening and deformation mechanisms of the hcp-high entropy alloys (HEAs) have not been elucidated yet because of the complexity introduced by the martensite structure, particularly in alloys undergoing phase transformation from bcc to hcp structures. This study attempted to fabricate an equiaxed hcp microstructure for TiZrHf, TiZrHfAl, and TiZrHfAlSc using the hot rolling process and subsequent heat treatment. The equiaxed hcp phase was successfully formed in TiZrHfAl, but the martensite structure remained in TiZrHf and TiZrHfAlSc. The 0.2 % proof stress at 400 and 600°C increased with the increase of the average atomic size misfit δ and the mixing entropy . The low activation volume and high-stress exponent of TiZrHfAl with equiaxed hcp phase at room temperature suggest minor obstacles such as cluster or short-range order inhibit the movement of dislocation and leading to the significant solid-solution strengthening. However, the effect diminished at 600 °C.

Tailored micro-arc oxidation coatings to match with parylene for enhanced tribological performance of Ta-12W alloys

To improve the tribological properties of tantalum-tungsten alloys, dual-layer composite coatings are designed using micro-arc oxidation (MAO) and chemical vapor deposition (CVD) techniques. By adjusting the concentrations of NaOH and NaF additives as well as the oxidation mode (constant current/voltage) of MAO process, the microstructure and properties of underlying MAO layers are tailored for better matching with the top parylene layer, aiming to develop composite coatings capable of service under heavy loads. A comprehensive study is conducted to evaluate the effect of these parameters on the growth, microstructure, bond strength, and mechanical properties of MAO coatings, along with their subsequent impact on the friction and wear behavior under various loads for composite coatings. The findings reveal that increasing the concentration of either NaOH or NaF significantly increases the coating thickness, surface porosity, crystallinity, and hardness of MAO coatings, by promoting the spark discharge activities. However, distinct interfacial growth behavior is observed due to anionic effects caused by OH− and F−. The oxidation mode plays a crucial role in determining the mechanical quality of coatings; the constant voltage mode facilitates dense coatings with high adhesion due to its self-repairing mechanism. Furthermore, wear tests confirm that the enhanced mechanical properties and open-porosity of the MAO coatings markedly improve the tribological performance of composite coatings. This improvement is attributed to the excellent load-bearing capacity provided by hard MAO layers, as well as the anchoring and storage capabilities of the textural porous surfaces. The optimized composite coating demonstrates long-lasting low friction even under heavy loads up to 80 N.

Anticorrosive Properties of Different ZnFeNi Alloys Synthesized on Carbon Steel Surface

ZnFeNi alloys were synthesized galvanostatically in a sulfate bath at constant current values of 1, 1.5, and 2 mA on the carbon steel surface. The synthesized alloys were characterized by scanning electron microscopy, energy-dispersive X-ray analysis, and linear sweep voltammetry methods. The corrosion performances of the alloys were examined by electrochemical impedance spectroscopy, anodic polarization curves, and open-circuit potential-time techniques. Based on the anodic polarization curves, it was determined that the alloy with the lowest corrosion current was the ZnFeNi-1.5 alloy synthesized at a constant current value of 1.5 mA. The electrochemical impedance spectroscopy results showed that the alloy with the highest polarization resistance during long exposure to a corrosive environment was ZnFeNi-1.5. By examining the anticorrosive properties, it was understood that the alloy that showed the best protective properties against the corrosion of carbon steel was ZnFeNi-1.5.

Microstructure and corrosion properties of CrMnFeCoNi high entropy alloy coating by temperature field-assisted laser cladding

The CrMnFeCoNi high entropy alloy coatings were prepared on the surface of Q345 steel using a temperature field-assisted laser cladding process, and the effects of the applied temperature field on the cladding coatings were studied. The microstructures and corrosion morphologies of the coatings were observed, and the elemental distribution, hardness, effective elastic modulus, electrochemical corrosion performance, and corrosion products of different coatings were analyzed. The results show that the porosity of the HEA coatings prepared with a temperature field is reduced to below 50 % of the initial level. The microstructure of the coating changed, with the nanoindentation hardness of the coating increasing by up to 0.55 GPa, enhancing the mechanical properties. Among all the coatings, the coating prepared at 250 °C temperature field exhibited the best corrosion resistance, with corrosion potential and current density of −0.27 V and 0.15 μA/cm2, respectively, improving the corrosion potential by 0.1 V and reducing the current density by 1.08 μA/cm2 compared to the sample prepared at room temperature. After incorporating the temperature field, the stability of the passive film on the coating during corrosion improved, and the nucleation rate of pitting decreased. Therefore, incorporating an appropriate temperature field during laser cladding can effectively enhance the overall performance of the CrMnFeCoNi HEA coating.

Influence of electric pulse on microstructural characteristics and mechanical properties of cast AZ91D magnesium alloy

Influence of electric pulse on microstructural characteristics and mechanical properties of cast AZ91D magnesium alloy

Radiation Shielding Properties of Nickel, Copper and Iron Based Alloys

This study explores the radiation shielding properties of Iron-based and Nickel-based alloys with Cobalt composition to evaluate their performance in photon attenuation and shielding applications. The objectives of this work are to determine linear and mass attenuation coefficients (LAC, MAC), half and tenth value layers (HVL, TVL), mean free path (MFP), effective atomic number and electron density (Zeff, Neff), effective conductivity (Ceff), atomic cross section (ACS) and electronic cross section (ECS) of nickel and iron base alloy with Cobalt using Phy-X/PSD within 0.001 MeV to 10 MeV. The result shows Iron and Nickel-based alloys have electron densities around 10²³ electrons per gram, with increased Iron concentration improving low-energy photon attenuation. Nickel-based alloys have a higher MAC and LAC compared to Iron-based oxides, indicating better photon absorption per unit mass and thickness, respectively. Nickel-based alloys exhibit a lower HVL and TVL, indicating greater attenuation and absorption efficiency for photons, especially at lower energies. Conversely, Iron-based alloys, while showing higher HVL and TVL. Nickel-based alloys exhibited higher electron densities the Iron-based alloys and Zeff values for Nickel based alloys, ranging from 27.1 to 27.8 while Iron-based alloys with Zeff between 26.2 and 26.8. Ceff in Iron-based alloys was stable at (1.50 to 1.74) x 10⁹ S/m, while Nickel-based alloys showed significant fluctuations below 0.01 MeV. Nickel-based alloys also had higher ACS and ECS, indicating superior photon interaction, especially at lower energies. These results highlight Nickel based alloys' greater efficacy in low-energy photon attenuation and the stable performance of Iron based alloys at higher energies.

Strengthening of mechanical and tribological properties in CrFeCuMnNi high entropy alloy through dispersion of TiO2 reinforcement via powder metallurgy processes

The present study reports the effect of TiO2 reinforcement on the phase, microstructure, mechanical and tribological properties of CrFeCuMnNi/TiO2 high entropy alloy composites (HEACs) processed by powder metallurgy. The results reveal the formation of single-phase face-centered cubic (FCC) structure after 30 h of milling in the original HEA, while TiO2 peaks in the HEACs indicate uniform distribution. After sintering, multiple phases including FCC, Cr-rich, Cr2O3 were observed. The hardness of HEAs increased from 330±10 to 440±10 HV and compressive yield strength increased from 480 to 760 MPa while scarifying the strain from 43.5 to 21 % with TiO2 content. The addition of TiO2 content slightly reduces the coefficient of friction and specific wear rate decreased by 45.16 % due to increased hardness and formation of stable oxide layer on the worn surface inhibits plastic deformation. The addition of TiO2 reduces the dominance of abrasive and adhesive wear and enhances the strength of HEACs.

Improvement of gradient microstructure and properties of wire-arc directed energy deposition titanium alloy via laser shock peening

Wire-arc directed energy deposition (WADED) technology has been widely used in the remanufacturing of titanium alloy structural components benefited from with the advantages such as high deposition efficiency and low cost. However, due to the coarse and anisotropic microstructure, the complex internal stresses and processing-induced rough surface significantly reduce fatigue performance and reliability of the remanufactured structural components. In this work, surface modification of titanium alloy WADED repair component was carried out via laser shock peening (LSP), and its gradient structure, microhardness, residual stress and fatigue performance and enhancement mechanism were systematically investigated. Results indicated that the different microstructure of each region led to different responses under the action of LSP, which was related to the change of dislocation density. LSP induced crystal defects such as high-density dislocations, twins and stacking faults on the surface. A variety of crystal defects gradually decreased with the depth from the strengthened surface, formed a gradient microstructure and significantly affected the microhardness and residual stress of the repaired components. The surface hardness and compressive residual stress of the repaired components were greatly increased after LSP and the hardened layer and compressive residual stress depth affected layer were 600 μm and 800 μm, respectively. The average fatigue life of the additive repair component increased by 197 % under the synergistic effect of compressive residual stress and gradient microstructure.

Effect of Er2O3 and Y2O3 on microstructure and mechanical properties of Ti2AlNb alloy

Rare earth oxides can significantly refine the microstructure of the cast alloys and improve their mechanical properties. In this study, Er2O3 and Y2O3 particles were chosen to add into the Ti2AlNb-based alloy with vacuum non-consumable arc melting method. For the Er2O3 particles, it has obvious dissolution and re-precipitation characteristics during melting. While for the Y2O3 particles, they are more stable, and aggregated and grew up during melting. These two kinds of Er2O3 or Y2O3 both have obvious refinement effects on the B2 grains due to their heterogeneous nucleation. Specially, adding Er2O3 particles can promote the decomposition of the B2 and α2 phases and the increases of the O-phase content. But adding the Y2O3 particles can inhibits the B2 decomposition and just only promotes the α2 decomposition into the O-phase. Additionally, the TAC-Er2O3 ingot shows the worst mechanical properties at room-temperature due to its large size and grain boundary segregation of the Er2O3 reinforcements. Conversely, the TAC-Y2O3 alloy exhibits excellent strength and ductility whatever at room- and high- temperatures owing to its fine grain strengthening and effective strengthening of the second precipitated Y2O3 phases.

A molecular dynamics study on mechanical performance and deformation mechanisms in nanotwinned NiCo-based alloys with nano-precipitates under high temperatures

Abstract Molecular dynamics simulations are performed to investigate the mechanical behavior of nanotwinned NiCo-based alloys containing coherent L12 nano-precipitates at different temperatures, as well as the interactions between the dislocations and nano-precipitates within the nanotwins. The simulation results demonstrate that both the yield stress and flow stress in the nanotwinned NiCo-based alloys with nano-precipitates decrease as the temperature rises, because the higher temperatures lead to the generation of more defects during yielding and lower dislocation density during plastic deformation. Moreover, the coherent L12 phase exhibits excellent thermal stability, which enables the hinderance of dislocation motion at elevated temperatures via the wrapping and cutting mechanisms of dislocations. The synergistic effect of nanotwins and nano-precipitates results in more significant strengthening behavior in the nanotwinned NiCo-based alloys under high temperatures. In addition, the high-temperature mechanical behavior of nanotwinned NiCo-based alloys with nano-precipitates is sensitive to the size and volume fraction of the microstructures. These findings could be helpful for the design of nanotwins and nano-precipitates to improve the high-temperature mechanical properties of NiCo-based alloys.