(1. 西南鋁加工廠技術(shù)中心， 重慶401326； 2. 中南工業(yè)大學(xué)材料科學(xué)與工程系，長沙410083)
摘 要: 研究了預(yù)拉伸量和時效溫度對CP276鋁鋰合金組織與性能的影響。結(jié)果表明，時效前的預(yù)拉伸可促進(jìn) T1相異質(zhì)形核，顯著提高合金的沉淀強(qiáng)化效果，但同時指出,過大的預(yù)拉伸量(＞6%)導(dǎo)致位錯胞狀纏結(jié), 降低 T1 相分布的均勻性，對合金性能不利。時效溫度則對晶界PFZ影響顯著，高溫時效的合金PFZ較寬，強(qiáng)度與塑性很差。該合金的最佳應(yīng)變時效制度為：3%～6%預(yù)拉伸＋160℃時效16～20h，該制度下合金具有較好的綜合力學(xué)性能(σb＝563MPa, σ0.2＝521MPa, δ＝6.6%)。
關(guān)鍵字: 鋁鋰合金；時效；組織；性能
（1. Technology Center, Southwestern Aluminium Fabrication Plant, Chongqing 401326, P.R.China
2. Department of Materials Science and Engineering,
Central South University of Technology, Changsha 410083, P.R.China）
Abstract:Effects of the pre-ageing stretch and ageing temperatures on the microstructure and mechanical properties for Al-Li alloy CP276 were investigated. The results show that stretch before ageing promotes the heterogeneous nucleation of T1 precipitates throughout the matrix and hence increases the ageing strengthening effect of this alloy significantly. However, over-stretching (＞6% ) results in cellular tangles of dislocations, which decreases the uniform distribution of T1 precipitates inside the grains, and therefore, deteriorates the strength and ductility of the alloy to some extent. The results also show that, ageing temperatures affect morphologies of precipitation free zones along grain boundaries remarkably. Alloy aged at high temperature exhibits wider PFZ , corresponding to the poor combination of strength and ductility. As a result, the favorable strain-ageing process for this alloy is that pre-ageing stretching 3%～6%＋ageing at 160 ℃ for 16～20 h, upon which the alloy achieves desirable strength-ductility balance, i.e., σb is 563 MPa, σ0.2 is 521 MPa, δ is 6.6%, respectively.
Key words: Al-Li alloys; ageing strengthening; structure; property
