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Predicting Thermal Conductivity of Metallic Glasses and Their Nanocomposites
Published in Sumit Sharma, Metallic Glass–Based Nanocomposites, 2019
Tregilgas [56] made a new kind of digital light processor. In this precious work, amorphous titanium-aluminide-based material was used and it was seen that it allows the rotation of each micromirror, and the life cycle was increased significantly. It was announced the winner of the 2004 ASM Engineering Materials Achievement Award. This technology has allowed digital cinema to become a reality. Dandliker et al. [57] demonstrated how to use bulk metallic glass composites as a penetrator efficiently. The amorphous composite comprises 41.25% atomic percent zirconium, 41.25% titanium, 13.75% copper, 12.5% nickel, and 22.5% beryllium. An excellent property exhibited by this composite is its use as a kinetic energy penetrator. Gorsse et al. [58] investigated the magnetocaloric effect and refrigeration capacity of Gd60Al10Mn30 nanocomposite. It was observed that it exhibits excellent refrigeration capacity with the soft magnetic characteristics, which allows it to be used in a wide range of temperatures. The ability to utilize this material as a magnetic refrigerant at 150 K is making the other materials a center of attraction.
Densification of Consolidated Products
Published in Anshuman Patra, Oxide Dispersion Strengthened Refractory Alloys, 2022
The applications of refractory alloys are extensive and every application has specific property requirements. The application of refractory alloys in high temperature applications, such as in aerospace, requires resistance against oxidation as well as sufficient high temperature strength. During oxidation of some refractory metals (W, Mo), the volatile constituents get removed as well as oxygen diffusion occurs through short-circuiting channels. The presence of porosities aggravates the oxidation further and may lead to premature failure of components. Therefore, superior densification reduces the oxidation as well as positively contributing to strength. Porosity facilitates crack nucleation and therefore enhancement of the impact toughness of W by increasing the density is a essential approach [51]. A report also suggests applying swagging and rolling as fabrication methods to improve the fracture strength [51]. During neutron irradiation in a nuclear reactor, both nanostructure grains and ductility are significant. High relative density (around 99.5%) is associated with the ductilization effect in refractory alloys [51]. The recent literature describes how through computational investigation the presence of compacted nanoparticles (52% densification with respect to bulk W) can be effective as plasma-facing material, owing to the rapid movement of point defects to the surface and eradication [52]. Superior density effectively inhibits radiation from high energy α and γ particles in a fusion reactor [53]. For a kinetic energy penetrator application, high density is an important aspect in achieving superior penetration depth. Fang et al. have studied the penetration performance between W alloys (90W–7Ni–3Fe and 80W–14Cu–6Zn) and indicate that the superior density (17 g/cm3) in 90W–7Ni–3Fe alloy reduces the impact velocity and penetration depth against 80W–14Cu–6Zn (density: 15 g/cm3), and specify that additionally self-sharpening behavior, quick plastic localization, and adiabatic shear band formation add to the improved penetration performance [54, 55]. Complete densification is also impervious to erosion and cracking in the application of refractory metal in a rocket nozzle, though the effectiveness depends on the flame temperature of the propellants [56]. W nozzles, fabricated by the powder metallurgy route with less density, erode through chemical reaction and mechanical abrasion mode and, conversely, W with a high density exhibits minor erosion through oxidation [56]. The presence of extensive voids or cavities may assist in reduced abrasion by facilitating crack propagation. W-25%Re alloy, developed by powder injection molding (PIM) followed by pressureless sintering and HIP for a rocket nozzle application, exhibits final percentage relative density of 99% and shows exceptional resistance to erosion (0.009 mm/s) [57].
Effect of Ni/Fe ratio on microstructure, tensile flow and work hardening behaviour of tungsten heavy alloys in heat treated and swaged conditions
Published in Philosophical Magazine, 2021
Ashutosh Panchal, K. Venugopal Reddy, P. A. Azeem, Rajdeep Sarkar, Archana Paradkar, T. K. Nandy, A. K. Singh
Developments of tungsten heavy alloys (WHAs) with improved static and dynamic mechanical properties have primarily been driven by the need for kinetic energy penetrator with enhanced ballistic performance. The first generation WHAs are based on ternary W–Ni–Cu alloys, which were subsequently replaced by W–Ni–Fe as the latter class of alloys exhibit superior mechanical properties [1]. Subsequently, alloys based on W–Ni–Fe have undergone several modifications with incorporation of alloying additions such as Mo, Re, Ta, Cr and Co [2–7]. Among these alloying elements, Mo and Co have received considerable attention [5,6]. The addition of Mo has resulted in increasing strength at the expense of ductility. This has been attributed to refinement in the W-grain size that in turn ascribes to reduce Ostwald ripening kinetics. The Co addition has led to enhancement of both the strength as well as ductility. Therefore, the alloying element Co has an important bearing on the evolution of WHAs resulting in several useful compositions based on W–Ni–Fe–Co [2–4]. The beneficial effect of Co has been attributed to enhanced solubility of W in matrix phase, which in turn results in microstructure with increased matrix volume fraction along with reduced W-W contiguity thereby leading to enhanced strength-ductility balance.