高Cu/Mg比AlCuMg合金的形变诱导Ω相析出强化

Deformation-induced Ω Phase Precipitation Strengthening of AlCuMg Alloy with High Cu/Mg Atomic Ratio

通过高分辨电子显微技术(TEM)、硬度测试、拉伸性能测试等手段研究了预变形对高Cu/Mg比AlCuMg合金180℃人工时效微观结构及力学性能的影响.结果表明,相对于传统时效T6处理,冷轧预变形(10%~60%)加后续人工时效的P-T6工艺使Al-CuMg合金的屈服强度提高了32%~69%,而延伸率保持在6%~13%.TEM表征发现T6工艺时效析出相为θ′相,而P-T6工艺时效析出相为Ω相和θ′相,Ω相的径厚比远大于θ′相,且数量上占总析出相的30%~75%.相对于θ′相而言,Ω相具有更好的强化能力和热稳定性.含Mg的AlCuMg合金可通过形变诱导Ω相析出,而不含Mg的AlCu合金不管是否变形均不析出Ω相.

The effect of pre-deformation on the age hardening behaviors, tensile properties and precipitate characteristics of an Al-Cu-Mg alloy with a high Cu/Mg atomic ratio during 180℃ artificial ageing was investigated by using transmission electron microscopy （TEM）, hardness test and tensile. The results show that room-temperature rolling of Al-Cu-Mg alloys with a thickness reduction of 10%~60% plus a subsequent artificial ageing （P-T6） can result in the strength increase of 32%-69% with elongation ranging from 6% to 13% compared with the conventional heat treatment process （T6）. Transmission electron microscopy （TEM） revealed the main precipitates are Ω and θ′ phase in P-T6 condition instead of θ′ phase in T6 condition. Furthermore, the aspect ratio of Ω phase is much bigger than θ′ and the number of Ω phase reaches the total precipitates of 30% ~75%. Compared with θ′ phase, Ω phase processes better precipitation strengthening and thermal stability. Ω phase can form through deformation-induced-precipitating in Al-Cu-Mg alloys, while Ω phase does not precipitate in Mg-free Al-Cu alloys with or without pre-deformation.