T6态Al_(2)O_(3np)/7075复合材料组织、力学及摩擦磨损性能研究

Study on the Structure,Mechanical and Friction and Wear Properties of T6 Treated Al_(2)O_(3np)/7075 Composite Materials

通过搅拌铸造工艺制备了2wt.%Al_(2)O_(3np)7075复合材料,然后对复合材料进行了T6热处理。利用扫描电子显微镜、透射电子显微镜、显微硬度计、拉伸试验机和多功能摩擦磨损试验机等分析测试仪器设备,对热处理前后Al_(2)O_(3np)/7075复合材料的微观组织、力学性能及摩擦磨损性能进行了研究。研究结果表明:Al_(2)O_(3np)的添加极大地细化了7075合金的α-Al晶粒的尺寸,对复合材料进行热处理之后,组织中元素成分偏析减少,MgZn_(2)析出相弥散分布于Al基体内。与Al_(2)O_(3np)/7075复合材料的力学性能相比,T6态复合材料的力学性能显著提高。在30 N、0.35 m/s的摩擦条件下,T6态复合材料的磨损率和摩擦系数分别为0.0116 mg/m和0.2528,与铸造复合材料相比磨损量和摩擦系数分别降低了64.19%和23.32%。铸态复合材料的磨损机制以粘着磨损为主,而T6态复合材料的磨损机制以轻微粘着磨损和磨粒磨损为主。

The 2wt.%Al_(2)O_(3np)/7075 composite was prepared by the stirring casting process,and then the composites were treated by T6 heat treatment.The microstructure,mechanical properties and friction and wear properties of Al_(2)O_(3np)/7075 composites before and after heat treatment were investigated by means of scanning electron microscopy,transmission electron microscopy,microhardness tester,tensile mechanical testing machine,and multifunctional friction and wear performance testing machine.The results showed that the addition of Al_(2)O_(3np)greatly refines the size of theα-Al grains of the 7075 Al matrix.After the T6 heat treatment of the composite,the segregation of element components in the microstructure reduced,and the precipitated phase of MgZn_(2)was uniformly distributed in the Al matrix crystal.Compared with the mechanical properties of Al_(2)O_(3np)/7075 composite,the mechanical properties of T6 heat treated composite increased significantly.Under the friction conditions of 30 N and 0.35 m/s,the wear and friction coefficients of T6 heat treated composites were 0.0116 mg/m and 0.2528,which were 64.19%and 23.32%less than those of as-cast composites,respectively.The wear mechanism of as-cast composite was adhesive wear,while the wear mechanism of T6 heat treated composite was slight abrasive wear and adhesive wear.