Al-2.3Cu-1.7Mg-1.2Fe-1.2Ni合金的时效行为研究

Aging Characteristics of Heat-Resistant Alloy Al-2.3Cu-1.7Mg-1.2Fe-1.2Ni

采用硬度测试、电导率测试、常温力学性能测试等方法研究了单级时效处理过程中时效温度和时效时间对Al-2.3Cu-1.7Mg-1.2Fe-1.2Ni合金力学性能和电导率的影响规律,并利用金相显微镜(OM)、扫描电镜(SEM)、透射电镜(TEM)、选区电子衍射(SAED)等手段对合金淬火态以及几种不同时效处理制度下的显微组织进行了研究。结果表明,合金经固溶淬火处理后仍残留有较多的大尺寸第二相,淬火态组织存在的第二相主要有Al9FeNi,Al7Cu2Fe,Al7Cu4Ni等。单级时效处理过程中,时效处理的温度越高,达到峰时效所需的时间越短,材料的峰时效硬度值越低;电导率随时效时间的延长而不断上升,时效温度越高,电导率的增长速率越快。峰时效条件下合金内主要沉淀强化相包括S'相和S″相,晶界上有明显的链状析出物存在,呈不连续分布;峰时效条件下,合金棒材的极限抗拉强度、屈服强度和延伸率分别为455 MPa,391 MPa和10.6%,电导率可达到21.6 MS.m-1。

Effect of one-step ageing treatment temperature and time upon mechanical properties and electrical conductivity of Al-2.3Cu-1.7Mg-1.2Fe-1.2Ni alloy was studied by means of hardness,electrical conductivity and mechanical properties testing,and the as-quenched microstructure and the as-aged microstructure of the alloy under various ageing tempers had also been studied by using optical microscopy（OM）,scanning electron microscopy（SEM）,energy dispersive spectroscopy（EDS） and transmission electron microscopy（TEM） analysis technologies.The results showed that some secondary phases presented in the alloy after solid solution heat treatment,which consisted of mainly Al9FeNi,Al7Cu2Fe and Al7Cu4Ni compounds.During the single aging process,the higher the ageing temperature,the shorter the peak ageing time.The hardness of the peak-aged alloy would be lower when the ageing temperature was higher.With the ageing time increasing,the electrical conductivity would increase.The higher the ageing temperature,the faster the speed rate of electrical conductivity increase.The strengthening precipitates of peak-aged alloy were S′ and S″ precipitates,and discontinuous catenarian S phases could be observed along the grain boundaries.Under the peak-aged condition,the ultimate tensile strength,yield strength,elongation and electrical conductivity could reach 455 MPa,391 MPa and 10.6% and 21.6 MS · m-1,respectively.