添加元素Ti的Mg-3Gd-2Zn-0.5Zr合金组织及力学性能研究

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

摘要:

本工作制备了Mg-3Gd-2Zn-0.5Zr-xTi（GZ32K-xTi）（x=0，0.5，1.0，1.5wt%）镁合金，研究了元素Ti添加量对铸态和挤压态GZ32K-xTi合金组织和力学性能的影响。随着元素Ti的加入，铸态GZ32K合金的α-Mg基体得到细化，晶界处不连续网状分布的W（Mg₃Zn₃Gd₂）相变得均匀细小，团簇状的Zr颗粒与Ti元素相互伴生且呈弥散分布；铸态GZ32K-1.5Ti合金中的α-Mg平均晶粒尺寸最小为49.84 μm，且尺寸分布最均匀。Ti元素的加入阻碍了动态再结晶的生长过程，使挤压后的GZ32K-xTi合金发生了完全再结晶，晶粒得到细化，同时发现Ti元素的加入促进了γ′相的析出。添加Ti元素的挤压态合金退火后，获得了含Ti的壳体结构纳米析出相，使得挤压态GZ32K-1.5Ti合金在退火后获得最佳的力学性能（YS=260.78 MPa，UTS=322.69 MPa，EL=15.17%）。该添加Ti元素的合金性能增强主要是由于晶粒细化、细小W相以及含Ti的壳体结构纳米析出相的存在。

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.