热处理对Mg_2B_2O_(5w)/6061Al复合材料组织和性能的影响

Effect of heat treatment on microstructure and properties of Mg_2B_2O_(5w)/6061Al composites

研究了单级固溶及峰值时效处理对粉末热挤压法制备5 vol%Mg2B2O5w/6061Al复合材料组织和力学性能的影响。结果表明:经粉末热挤压制备的材料,晶须分布相对均匀,但长径比显著降低,材料主要由α(Al)、Mg2B2O5w和Mg2Si相为主;热挤压态复合材料经固溶时效(510℃×1 h+160℃×9 h)处理后,晶粒内部析出大量的β'相;拉伸强度、屈服强度和伸长率分别为357.6 MPa、205 MPa和8.77%,相比挤压态复合材料,拉伸强度和屈服强度分别提高了81%和78%;拉伸断口分析表明,材料的失效形式以基体的韧性断裂和晶须团聚体的脆性开裂为主。

Effects of solution treatment and aging process on microstructure and mechanical properties of powder hot extruded 5 vol%Mg2B2O5w/6061Al matrix composite were investigated by X-ray diffractometer,scanning and transmission electron microscope,macrohardness and tensile tests.The results show that the whiskers are distributed homogeneously with decreasing aspect ratio in 6061 Al matrix during extrusion,and the composite is composed of matrix phase α( Al),Mg2B2O5wand nominal Mg2Si phase.A large number of β'phases are precipitated from Al matrix after solution and aging treatment( 530 ℃ × 1 h + 170 ℃ × 6 h).Tensile strength,yield strength and elongation of the composites are 357.6 MPa、205 MPa and 8.77%,respectively.In contrast with as-extruded materials,the tensile strength and yield strength of the heat treate composites increase by 81% and 78%.According to the analysis of fracture,the ductile failure of 6061Al matrix and the reinforcement fracture act as the main mechanism of fracture nucleation.