Infiltration of magnesium-zinc and magnesium-aluminum alloys into titanium powder preforms using indirect selective laser sintering

Abstract

In this study, we attempted to infiltrate molten magnesium-zinc (Mg-6.2 mass%Zn) alloy and magnesium-aluminum (Mg-8.3 mass%Al) alloy into titanium powder preforms using indirect selective laser sintering (SLS). It was observed that molten Mg-Zn and Mg-Al alloys could easily infiltrate the Ti powder preforms during self-activation at 973 K under argon atmosphere. In addition, all of the infiltrated sections of the preforms were found to exhibit excellent dimensional accuracy. The hardness and tensile strength of the infiltrated portions of Mg-Zn were found to be 71 HRB and 333 MPa, respectively, and the corresponding values for Mg-Al alloy were 71 HRB and 343 MPa, respectively. The tensile strengths of the parts of the preform infiltrated with an alloy were significantly higher than those of the parts infiltrated with just Mg (241 MPa). We believe that the large increase in tensile strength after Mg-Zn and Mg-Al infiltration is due to the interfacial reinforcement of the matrix and the generation of Ti-based intermetallic phases, such as TiZn3, TiAl, and TijAl, on the surface of Ti particles as a result of their reaction with molten alloys. As a consequence of the reaction with molten alloys, the Zn or Al concentration in the infiltrated parts of the matrix was found to be lower than before infiltration. Thus, the infiltration of the Mg-Zn and Mg-Al alloys into Ti powder preforms can be considered an effective indirect SLS technique for producing lightweight infiltrated metal alloy parts.