Liquid Phase Sintering of a novel Tungsten Heavy Alloy with High Entropy Alloy as Binder

Abstract

High entropy alloys (HEA) are a new class of materials, in which five or more principle elements are incorporated in equal or near equal atomic (%) ratios. Unlike conventional alloys, with one principle element, these alloys offer an exciting set of properties without compromising on existing ones. Hence, HEA warrant their exploration for systems that have previously been researched and still require improvements in their properties. Tungsten heavy alloys have been the industrial standard for applications, requiring high density, vibration damping, counter balancing, kinetic energy penetrators etc. However, for kinetic energy penetrators depleted uranium are still the best contender than tungsten heavy alloys. Currently, tungsten heavy alloys are being manufactured as composites; wherein, tungsten particles are embedded inside ductile matrix of a fcc Ni-Fe alloy system, in which Co and Mn are added to improve mechanical properties of the composite. Keeping in view the presence of four elements in the binder matrix of conventional tungsten heavy alloy, this research work aimed at studying the possibility of manufacturing a high entropy alloy-based matrix by adding Cr into the basic four elemental system by keeping the inclusion of each element between 14% - 22% atomic. The powders after mixing were subjected to undergo liquid phase sintering under two different environments i.e. pressure-less sintering and hot iso-static pressing (HIP) sintering, respectively. Microstructure was analyzed by SEM/EDS, crystal structure and phase analysis were conducted through XRD analyses. The mechanical tests in regimes of hardness, impact and compression were conducted and the results were compared with the conventional tungsten heavy alloys. Liquid phase sintering under HIP sintering was found to be successful in obtaining the classic liquid phase sintered structure, in which tungsten particles are embedded inside binder matrix.