2A14铝合金TTT曲线及其淬火敏感性

摘要

Quenching sensitivity of 2A14 aluminum alloy was determined by time-temperature-transformation (TTT) curve,which was carried out by an interrupted quench method.XRD,TEM and EDS were applied to investigate the microstructure of 2A14 aluminum alloy,and the isothermal phase transformation kinetics were studied by Avrami equation.The results showed that the nose temperature of TTT curve was 350 ℃ and the quench sensitive temperature range was 300-400 ℃.In addition,the supersaturated solid solution decomposed and precipitated quickly at 350 ℃,due to higher degree of supersaturation and fast diffusion rate.Furthermore,this work suggests that for 2A14 aluminum alloy,residual stress and mechanical properties can be balanced by increasing cooling rate within quenching sensitivity range (300-400 ℃) and reducing cooling rate in other temperature ranges.%采用分级淬火实验方法,绘制了2A14铝合金时间-温度-转换率(TTT)曲线,利用XRD、TEM、EDS等观察分析了合金等温过程中的组织变化,结合Avrami方程研究了等温过程中相变动力学.结果表明合金TTT曲线鼻尖温度为350℃,淬火敏感区间为300～400℃.2A14铝合金过饱和固溶体在350℃等温处理时快速分解,第二相脱溶析出速率达到最高.鼻尖温度较大的过饱和度和较高的扩散速率是第二相快速析出和长大的主要原因.2A14铝合金淬火过程中,建议在淬火敏感区间(300～400℃)提高冷却速率抑制第二相析出,在其他温度区间适当降低冷却速率,以获得较高的综合性能.