Study on the Microstructure and Mechanical Properties of Mg-3Gd-2Zn-0.5Zr Alloy with the Addition of Element Ti

Abstract:

In this work, Mg-3Gd-2Zn-0.5Zr-xTi (GZ32K-xTi) (x=0, 0.5, 1.0, 1.5wt%) alloys were prepared, and the effect of Ti addition on the microstructure and mechanical properties of as-cast and extruded GZ32K-xTi alloys was investigated. The results indicate that with the addition of element Ti, the α-Mg matrix of as-cast GZ32K-xTi alloy is refined, the discontinuous network distribution of W(Mg₃Zn₃Gd₂) phase at the grain boundary becomes uniform and fine, and the clustered Zr particles and element Ti are accompanied by each other and diffusely distributed. The average grain size of α-Mg in as-cast GZ32K-1.5Ti alloy is the smallest of 49.84 μm, and the size distribution is the most uniform. The addition of Ti hinders the growth process of dynamic recrystallization, which causes the complete recrystallization of the extruded GZ32K-xTi alloys and the refinement of the grains, and promotes the precipitation of the γ′ phase. After annealing of the extruded alloy with element Ti, the nanoprecipitate phase of the shell structure containing Ti is obtained, so that the best mechanical properties of the extruded GZ32K-1.5Ti alloy are obtained after annealing (YS=260.78 MPa, UTS=322.69 MPa, EL=15.17%). The enhancement of mechanical properties of the alloys with Ti is mainly due to the grain refinement, fine W phase and the Ti-containing nanoprecipitate phase with shell structure.