Achieving high strength and ductility in ODS-W alloy by employing oxide@W core-shell nanopowder as precursor

With excellent creep resistance, good high-temperature microstructural stability and good irradiation resistance, oxide dispersion strengthened (ODS) alloys are a class of important alloys that are promising for high-temperature applications. However, plagued by a nerve-wracking fact that the oxide particles tend to aggregate at grain boundary of metal matrix, their improvement effect on the mechanical properties of metal matrix tends to be limited. In this work, we employ a unique in-house synthesized oxide@W core-shell nanopowder as precursor to prepare W-based ODS alloy. After low-temperature sintering and high-energy-rate forging, high-density oxide nanoparticles are dispersed homogeneously within W grains in the prepared alloy, accompanying with the intergranular oxide particles completely disappearing. As a result, our prepared alloy achieves a great enhancement of strength and ductility at room temperature. Our strategy using core-shell powder as precursor to prepare high-performance ODS alloy has potential to be applied to other dispersion-strengthened alloy systems.

Investigation on Biocompatibility and Mechanical Properties of Ti15Mg Alloy

In this research work, bioactive Ti15Mg alloy was prepared by powder metallurgy route to investigate its biocompatibility and mechanical properties. Many tests were performed including X-ray diffraction; optical microscope analysis, scanning electron microscope analysis, ultrasonic wave test, corrosion behavior test, Static immersion test, and the wet sliding wear test. The XRD result shows that the prepared alloy sample consist of (α-Ti phase) and Mg. The microstructure of the prepared alloy sample consisted of a biodegradable Mg or pore and alpha titanium. The effect of the Mg content on degradability was tested based on simulated body fluid of Ringer solutions using electrochemical corrosion. The findings indicate that an elastic modulus of 47GPa exhibits the alloy. There were low corrosion rates of the alloy. The Ti matrix remained integrity after 14 days of immersion in the Ringer solutions, and the magnesium phase dissolved in the solution, causing a layer to form on the alloy. The wear behavior of the prepared ally at wet sliding conditions was evaluated using pin on disc method. The in vitro analysis showed good biocompatibility with Ti15Mg alloy. The prepared alloy demonstrates good biocompatibility and bioactivity.

Effects of modifying the hypoeutectic AlMg5Si2Mn alloy via addition of Al10Sr and/or Al5TiB

This work demonstrates that the combined addition of Al10Sr and Al5TiB master alloys to the AlMg5Si2Mn effectively refines the grain microstructure and partially modifies the eutectic Mg2Si phase. Thorough spectroscopic characterization reveals that the grain refinement effect is due to Al3Ti particles acting as nucleation sites for α-Al grains, and the increased nucleation temperature of α-Al is due to Al10Sr addition. It is also determined that TiB2 particles can act as nucleation substrates for the primary Mg2Si phase. The prepared alloy sample with the finest microstructure (treated with both Al10Sr and Al5TiB) exhibits the greatest corrosion resistance among all tested samples.

Thermal and microstructural analysis of the low-melting Bi-In-Pb alloy

Low-melting alloys, based on bismuth and indium, have found commercial use in soldering, safety devices, coatings, and bonding applications. In this respect, the accurate knowledge of their thermal properties such as melting and solidification temperatures, latent heat of melting, supercooling tendency, etc. is of large importance. In the present research, low-melting alloy with nominal composition Bi40In40Pb20 (at. %) was investigated by means of scanning electron microscopy (SEM) with energy dispersive X-ray spectrometry (EDS) and by differential scanning calorimetry (DSC). Microstructural and chemical (SEM-EDS) analysis has revealed the existence of two coexisting phases in the prepared alloy, which was identified as BiIn and (Pb). Melting and solidification temperatures and the related heat effects were measured by the DSC technique. The solidus temperature obtained from the DSC heating curves was 76.3 °C and the solidus temperature obtained from the corresponding DSC cooling runs was 61.2 °C. The experimentally obtained results were compared with the results of thermodynamic calculation according to CALPHAD (calculation of phase diagram) approach, and a close agreement was noticed.

W2C/WS2 Alloy Nanoflowers as Anode Materials for Lithium-Ion Storage

Recently, composites of MXenes and two-dimensional transition metal dichalcogenides have emerged as promising materials for energy storage applications. In this study, W2C/WS2 alloy nanoflowers (NFs) were prepared by a facile hydrothermal method. The alloy NFs showed a particle size of 200 nm–1 μm, which could be controlled. The electrochemical performance of the as-prepared alloy NFs was investigated to evaluate their potential for application as lithium-ion battery (LIB) anodes. The incorporation of W2C in the WS2 NFs improved their electronic properties. Among them, the W2C/WS2_4h NF electrode showed the best electrochemical performance with an initial discharge capacity of 1040 mAh g−1 and excellent cyclability corresponding to a reversible capacity of 500 mAh g−1 after 100 cycles compared to that of the pure WS2 NF electrode. Therefore, the incorporation of W2C is a promising approach to improve the performance of LIB anode materials.

Phase transformations and microstructural evolution in nanocrystalline Fe71B23Nb6 alloy prepared by mechanical alloying

A new nanocrystalline Fe71B23Nb6 alloy powder was prepared by mechanical alloying. The phase transformation and morphological and microstructural properties of the as-prepared alloy were investigated by scanning electron microscopy, laser granulometry, and X-ray diffraction with respect to the milling time (0- 200 h). During the milling process, it was observed that the dissolution of Nb and B atoms into the Fe matrix formed solid solutions of Fe (Nb), Fe (B), Fe23B6, Fe2B, and Fe (Nb, B). Moreover, the insertion of B atoms into the Nb network generated the Nb (B) phase. Furthermore, the minimum crystallite size was measured as approximately 1 nanometer. In addition, the dislocation density gradually increased with the extension of the milling time, and the crystallization of the partially amorphous phase occurred after 200 h of milling.

Influence of Thermal Annealing on Structural and Optical Properties of Sb Doped ZnTe Thin Film

Paper presents the influence of thermal treatment on structural and optical characteristics of Sb0.5ZnTe thin film. Alloy of Sb0.5ZnTe has been prepared through traditional and economical melt quenching technique and thin films of prepared alloy was deposited onto glass substrate by thermal evaporation method at pressure of 10–6 Torr. The antimony doped films were annealed for 2 h at three different temperatures ranges (373 K, 393 K and 413 K). Structural characterization of as prepared and annealed film was done by XRD technique and it was found that annealing improves the film crystal structure. UV-Vis spectrophotometer facilitates optical analysis of Sb0.5ZnTe film in wavelength range of 400–1000 nm. It was observed that band gap Eg of the Sb doped film increased while absorption coefficient (α) decrease with increase in heating temperature. These changes in optical properties were explained in terms of defect states.

Microstructure of a V-Containing Cobalt Based Alloy Prepared by Mechanical Alloying and Hot Pressed Sintering

In this paper, a bulk V-containing cobalt-based alloy with high chromium and tungsten contents was prepared by mechanical alloying and hot pressed sintering using Co, Cr, W, Ni, V and C pure element powders. XRD, SEM, TEM and Vickers hardness tests were employed to characterize the microstructure and mechanical properties of the mechanical alloyed powders and hot pressed bulk cobalt-based alloy. The results show that all elements can be mixed uniformly and that the Co, Cr, and Ni elements were made into an amorphous state after 10 h ball milling in a high energy ball miller. The microstructure of the prepared bulk alloy was composed of a γ-Co matrix with a large number of nano-twins and fine M23C6 and M12C carbide particles well-distributed in the alloy. The V element was mainly distributed in M23C6-type carbide and no V-rich MC-type carbide was found in the microstructure. The prepared alloy had a high hardness of 960 ± 9.2 HV and good a fracture toughness KIc of about 10.5 ± 0.46 MPa·m1/2. The microstructure formation and strengthening mechanisms of the prepared cobalt-based alloy are discussed.

Studying the Effect of Different Combinations of Salt Modifier on the Mechanical Properties and Microstructure of A356 Al-Si Alloy

The present study aims to develop A356 Al-Si alloy using high purity aluminium and various master alloy in gas fired pit furnace. Three different ratio of salt modifier (1:1, 1:2 & 1:3) was used to prepare the casting. Sand casting and permanent mould casting techniques were used to prepare the alloys. Optical microscope and universal tensile testing machine were used for the metallurgical evaluation of the prepared alloy. It was observed that the addition of modifier improved the mechanical properties and microstructure of the alloy. It was also observed that modifying agent NaF with CaCl2in 1:1 ratio has shown the best results in terms of microstructure and the mechanical properties.

A Novel High-Entropy Alloy AlMgZnSnPbCuMnNi with Low Free Corrosion Potential

A novel AlMgZnSnPbCuMnNi high entropy alloy was prepared by flux melting in the atmosphere. The microstructure and the electrochemical performances of the as-prepared alloy were studied by electrochemical workstation, X-ray diffraction and scanning electron microscopy. It was found that the free corrosion potential is as low as-1.33V in the 3.5%NaCl solution in spite of the content of Al, Mg and Zn element of the high entropy alloy is far below than that of the traditional zinc or aluminum sacrificial anode material while the free corrosion current density is 2.93×10-5 A/cm2 which is close to the typical aluminum sacrificial anode material.