The effect of Al content on Ti/Zr-based bulk metallic glass composite by additive manufacturing

In order to improve the amorphous phase-forming ability of in situ β-phase-reinforced Ti/Zr-based bulk metallic glass composites (BMGCs), a large amount of toxic Be element is traditionally used. In this study, Ti/Zr-based BMGCs with no toxic Be, (Ti_0·65Zr_0.35)_100-x-yCu_xAl_y (x = 5, 10; y = 1, 3, at. %, denoted Cu5Al1, Cu5Al3, Cu10Al1, Cu10Al3), were fabricated by selective laser melting (SLM). The effect of Al content on the microstructural evolution and mechanical properties were investigated. Compared to Cu, the increase in Al content had a smaller effect on the microstructural characteristics. However, for a constant Cu content, an increase in Al improved the amorphous phase forming ability and suppressed the precipitation of the (Ti, Zr)₂Cu phase, enhancing the α phase. The αʹ and α" martensitic phases precipitated in the β phase during the SLM process. In the compression tests of the Cu5Al1 and Cu5Al3 deposits, Al content was found to reduce the yield strength, increase the plastic strain, and improve the strain hardening exponent. Compared with the Cu10Al1 deposit, the plastic deformation capability of the β phase sharply decreased during the SLM process as a result of a large number of α" martensitic phases precipitating and the formation of cracks in the Cu10Al3 deposit. Compared to Be, Al was not enriched in the residual liquid phase during the growth of the β phase, which led to a slow increase in the viscosity of the residual liquid and a weaker effect on the amorphous phase formation ability.