Effects of Al replacement on glass forming ability and mechanical properties of Zr-based bulk metallic glasses

In this present study, the effects of Al substitution for Zr in Zr73-xCu12Ni12AlxNb3 (x=7.5, 10, 12.5, 15, 17.5 at.%) metallic glasses on the glass-forming ability, thermal stability, quasi-static and dynamic mechanical properties were investigated. Proper Al replacement improved the glass-forming ability, crystallization activation energy and mechanical properties of the amorphous alloys. Compared with quasi-static compression, due to the shorter loading time and more significant adiabatic temperature rise, the fracture strength decreased and no dynamic compression plasticity was observed for all alloys subjected to dynamic loading. From the aspect of atomic structure, the substitution of appropriate amount of Al not only promoted the formation of the stable short-range ordering (SRO) structure, but also changed the content and distribution of the free volume, which resulted in the improvement of GFA, strength and plasticity of the amorphous alloy.