800 MPa级超高强度铝合金的时效析出行为

采用硬度、电导率、室温拉伸测试方法,研究110~140℃范围内时效不同时间后新型铝合金性能的变化。利用透射显微镜(TEM)观察合金的组织形貌特征。结果表明:该新型铝合金最佳的时效工艺为110℃保温24 h,此条件下合金的抗拉强度,屈服强度和伸长率分别为808,785 MPa与6.9%。时效温度是影响合金析出相种类、密度和尺寸的主要因素。在110℃时效时,合金主要的析出相是GPⅠ区、GPⅡ区和亚稳η′相。110℃时长时间(直至96 h)时效后,GPⅠ区和GPⅡ区仍能稳定存在。与110℃时效相比,在140℃时效时,析出过程加速。当140℃时效4 h后,未观察到GP区的存在,主要的析出相为η′相;140℃时效24 h后,主要的析出相为η′相和η相。

Aging precipitation behavior of 800 MPa grade ultra high strength aluminum alloy

The hardness,conductivity and room temperature tensile test were used to study the properties of the new aluminum alloy aged at 110-140℃ for different time.The microstructure of the alloy was observed by transmission microscope(TEM).The results show that the optimum aging process of the new aluminum alloy is aging at 110℃ for 24 h.Tensile strength,yield strength and elongation are 808,785 MPa,6.9%,respectively.Aging temperature is the main factor affecting the type,density and size of precipitates.When aged at 110℃,the main precipitations are GPⅠ zones,GPⅡ zones and metastable η′phase.After aging at 110℃ for a long time(up to 96 h),GPⅠ zones and GPⅡ zones still exist stably.Compared with aging at 110℃,the precipitation process accelerates at 140℃.After aging at 140℃ for 4 h,no GP zone is observed,and the main precipitate phase is η′.After aging at 140℃ for 24 h,the main precipitates are η′phase and η phase.