多道次热挤压制备Al2O3/AZ31复合材料的微观组织与力学性能

Microstructure and mechanical properties of Al2O3/AZ31 composites prepared by multi-pass hot extrusion

采用多道次热挤压制备Al 2O 3颗粒增强AZ31镁基复合材料,利用OM,SEM,TEM对Al 2O 3/AZ31复合材料进行组织观察,利用维氏硬度仪、电子万能拉伸试验机对Al 2O 3/AZ31复合材料进行力学性能测试。结果表明:经过多道次热挤压后,Al 2O 3颗粒均匀地分散在AZ31镁基体中,Al 2O 3颗粒对基体组织的晶粒细化作用得到增强,复合材料的晶粒尺寸随着道次的增加而显著减小。经过4道次热挤压后,Al 2O 3/AZ31复合材料的力学性能显著提高,其硬度,抗拉强度和屈服强度分别达到89HV,305MPa和198MPa,相比于第1道次热挤压后,其硬度,抗拉强度和屈服强度分别提高了19.2%,14.8%和14.1%。

Multi-pass hot extrusion was used to prepare the Al 2O 3/AZ31 composite.The microstru-cture was characterized by optical microscopy,scanning electron microscopy,transmission electron microscopy,and mechanical properties were tested by Vickers hardness tester and electron universal strength tester.The results show that Al 2O 3 particles are uniformly distributed in AZ31 magnesium matrix by multi-pass hot extrusion.The grain refining effect of Al 2O 3 particles on the matrix is enhanced,and the grain size of the composite decreases significantly with the increase of the pass.During the hot extrusion process,the dislocation density around the Al 2O 3 particles increases,and the high-density dislocation region facilitates the dynamic recrystallization nucleation,so that the grains of the Al 2O 3/AZ31 composite are significantly refined.The Al 2O 3 particles are gradually distributed into a long strip from the initial island distribution,then distributed in a linear pattern,and finally distributed uniformly in the form of particles in the AZ31 magnesium matrix.After fourth-pass hot extrusion,the mechanical properties of Al 2O 3/AZ31 composite are significantly improved,and hardness,tensile strength and yield strength are 89HV,305MPa and 198MPa,respectively.The hardness,tensile strength and yield strength increase by 19.2%,14.8%,and 14.1%,respectively,compared with the first-pass hot extrusion.