高压扭转法制备非均匀层状结构Al-Zn-Mg-Cu-Zr合金的组织演变与力学性能

Microstructure Evolution and Mechanical Properties of Al-Zn-Mg-Cu-Zr Alloy of Heterogeneous Lamellar Structure Processed by High Pressure Torsion

摘要:

采用透射电子显微镜（TEM）、电子背散射衍射（EBSD）和Instron试验机对试验温度400 ℃下高压扭转变形加工的Al-Zn-Mg-Cu-Zr合金进行组织和力学性能的表征与测试。结果表明，变形试样的晶界和晶粒中的第二相明显被破碎和细化，晶界无沉淀析出带宽度变窄，大大提高了变形试样的强度和塑性。初始样品的晶粒取向是随机分布的。当应变较小时，试样的晶粒尺寸、晶粒取向和局部取向差异均呈现非均匀的片层状分布。由于非均匀层状组织在变形过程中产生的背应力强化效应，0.5圈变形试样的力学性能最好。

Abstract:

The microstructures and mechanical properties of the Al-Zn-Mg-Cu-Zr alloy processed by high pressure torsion (HPT) at 400 °C were analyzed by transmission electron microscopy (TEM), electron back-scattered diffraction (EBSD), and Instron testing machine. The results show that the grain boundaries and the secondary phases in the grains of deformed specimens are significantly broken and refined, and the width of precipitation-free zones at the grain boundaries narrows, which greatly improves the strength and plasticity of the deformed specimens. The grain orientation of the initial specimen is randomly distributed. When the strain is small, the grain size, grain orientation, and the local orientation difference of the specimen all present heterogeneous lamellar distribution. The deformed specimens of 0.5 turn exhibit the optimal mechanical properties due to the back stress strengthening effect caused by the heterogeneous lamellar structure during deformation.