Microstructure and mechanical properties of Al2O3 dispersed fine-grained medium heavy alloys with a superior combination of strength and ductility

Abstract

Abstract The medium W content W–Ni–Fe alloys have a combination of high strength and great ductility, revealing a promising future for widespread engineering applications. In order to fabricate medium W content W–Ni–Fe alloys with outstanding performances, W nano-powders prepared by a two-stage reduction method was employed as raw material. Meanwhile, the finely dispersed Al2O3 particles have effective roles in restraining the growth of W grain. Electron back-scattered diffraction analysis identified that fine W grains were uniformly distributed in the γ matrix phase without any observable texture. Benefitting from the combination of fine-grain strengthening, oxide dispersion strengthening and precipitation strengthening, a highest tensile strength of 816\xa0±\xa011\xa0MPa and a greatest elongation of 29.7\xa0±\xa01.2% are obtained for the sintered alloys of 75\xa0W–1Al2O3 and 50\xa0W, respectively. It is also concluded that the main fracture modes of the currently manufactured alloys are ductile matrix rupture and W-matrix interface separation.