摘要
The effect of temperatures and time of post-process aging on the microstructure,mechanical properties and wear behavior of friction stir processed 7075 Al alloy was investigated,using optical microscopy（OM）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM） and Vickers microhardness tester.The results indicate that homogeneous,equiaxed and fine recrystallized microstructure is obtained with the grain size of 4-5 μm.The hardness value increases up to 30% and 80% in the stir zone and the base material,respectively.Based on the TEM observations,it is concluded that the improved properties following the duplex friction stir-aging process can be attributed to the very fine precipitates.Comparing the single and double aging conditions,the hardness of single aging sample is higher than that of double aging one which can be attributed to the high fraction of very fine spheroidal precipitate in single aging sample.The wear rate is reduced by the aging of Al alloy and a more decrease is achieved after the aging of FSPed sample.
使用光学显微镜、扫描电镜、透射电镜和维氏硬度测定仪研究后处理时效温度和时间对搅拌摩擦加工7075铝合金的显微组织、力学性能和耐磨性的影响。结果表明,搅拌摩擦加工可获得均匀的、细小等轴再结晶显微组织,晶粒尺寸为4~5μm。在搅拌区域和母材中的硬度值分别增加了30%和80%。基于透射电镜观察,推断出摩擦搅拌加工-时效处理对性能的改进归因于细小析出相。比较单一和双重时效条件,发现单一时效样品的硬度高于双重时效样品的硬度,这归因于单一时效样品中高体积分数的细小球状析出相。时效能降低铝合金磨耗率,且搅拌摩擦加工样品时效后其磨耗率降低更多。
