Correlation of microstructure with dynamic deformation behavior and penetration performance of tungsten heavy alloys fabricated by mechanical alloying

In this study, tungsten heavy alloy specimens were fabricated by mechanical alloying (MA), and their dynamic torsional properties and penetration perf ormance were investigated. Dynamic torsional tests were conducted on the sp ecimens fabricated with different sintering temperatures after MA, and then the test data were compared with those of a conventionally processed speci men. Refinement of tungsten particles was obtained after MA, but contiguity was seriously increased, thereby leading to low ductility and impact energ y. Specimens in which both particle size and contiguity were simultaneously reduced by MA and two-step sintering and those having higher matrix fracti on by partial MA were successfully fabricated, The dynamic test results ind icated that the formation of adiabatic shear bands was expected because of the plastic localization at the central area of the gage section. Upon high speed impact testing of these specimens, self-sharpening was promoted by th e adiabatic shear band formation, but their penetration performance did not improve since much of kinetic energy of the penetrators was consumed for t he microcrack formation due to interfacial debonding and cleavage fracture of tungsten particles. In order to improve penetration performance as well as to achieve self-sharpening by applying MA, conditions of MA and sinterin g process should be established so that alloy densification, particle refin ement, and contiguity reduction can be simultaneously achieved.