Defects in the high entropy alloy HfNbTaTiZr prepared by spark plasma sintering

Abstract

Samples of HfNbTaTiZr alloys were prepared by spark plasma sintering using two powders. This resulted in very different microstructures, phase compositions and microhardnesses of the sintered samples. While the sample sintered from gas atomized powder exhibits two bcc phases with similar composition and lattice parameters, the sample sintered from mechanically alloyed powder resulted in a very fine structure consisting of three distinguished phases and achieved very high hardness. Positron annihilation spectroscopy was used in order to explain the nature of the defects and microstructure of HfNbTaTiZr alloys prepared by spark plasma sintering.