微量Ag对Al-Cu-Mg-Mn合金时效析出及组织热稳定性的影响

Effects of Ag Addition on Ageing Precipitation and Microstructure Thermal Stability of an Al-Cu-Mg-Mn Alloy

采用差热分析(DSC)及透射电镜(TEM),研究了微量Ag对Al-5.3Cu-0.8Mg-0.5Mn-0.5(Zr+Ti)合金时效析出过程及显微组织热稳定性的影响。结果表明,添加微量Ag可改变合金的时效过程,提高合金的时效硬化能力。含0.6%Ag的Al-Cu-Mg-Mn合金在185℃峰时效时的强化析出相由Ω相与少量θ′相组成,Ω相呈薄片状,该相{001}Ω面与基体Al的{111}α面共格,位向关系为(001)Ω//(111)α、[010]Ω//[101-]及[100]Ω//[12-1]α。当温度低于300℃时,Ω相比θ′相具有更好的热稳定性;而在300℃经长时间处理时,Ω相变得不稳定并最终转变成θ′相。

The effects of Ag addition on the aging precipitation and microstructure thermal stability of Al-5.3Cu-0. 8Mg- 0.5Mn-0.5 （Zr ＋ Ti） alloy were studied by differential scanning calorimetry and transmission electron microscopy. The results show that Ag addition changes the aging process and improves the aging hardening ability of the alloy. When Al- Cu-Mg-Mn with 0. 6% Ag alloy is under 185 ℃ peak ageing,the precipitate phase comprises the plate-like Ω phase and a small amount of θ＇phase. The Ω phase {001}Ω is coherent with the {111}α planes of Al matrix. The orientation relationship between the Ω phase and the Al matrix is ： （001） Ω//（ 111 ） α, （010） Ω//（ 101 ）及[ 100 ]Ω//[ 121 ]α. The thermal stability of the Ω phase is better than that of the θ＇phase when the temperature is below 300 ℃. However, after long time treatment at 300 ℃ ,the Ω phase becomes unstable and finally transforms into the θ＇ phase.