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

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 ± 11 MPa and a greatest elongation of 29.7 ± 1.2% are obtained for the sintered alloys of 75 W–1Al2O3 and 50 W, respectively. It is also concluded that the main fracture modes of the currently manufactured alloys are ductile matrix rupture and W-matrix interface separation.