(1. 中南大學(xué) 輕合金研究院，長(zhǎng)沙 410083；
2. 中南大學(xué) 材料科學(xué)與工程學(xué)院，長(zhǎng)沙 410083；
3. 中南大學(xué) 高性能與復(fù)雜制造國(guó)家重點(diǎn)實(shí)驗(yàn)室，長(zhǎng)沙 410083)
摘 要: 采用光學(xué)顯微及透射電子顯微、拉伸力學(xué)性能、維氏硬度等測(cè)試技術(shù)，研究Al-Cu-Li合金在蠕變時(shí)效過(guò)程中拉伸性能演變規(guī)律與微觀組織特征。結(jié)果表明：在蠕變時(shí)效過(guò)程中，合金的硬度和強(qiáng)度呈現(xiàn)先升高，到達(dá)峰值之后再緩慢下降的趨勢(shì)。其中CA2試樣(2%預(yù)變形再進(jìn)行蠕變時(shí)效)在16 h達(dá)到了蠕變時(shí)效硬度與強(qiáng)度峰值，比CA1試樣(不預(yù)變形直接進(jìn)行蠕變時(shí)效)提前了4 h，且CA2試樣的峰值區(qū)域更為明顯。相比于CA1試樣，CA2試樣的硬度和強(qiáng)度提高，伸長(zhǎng)率降低。在峰值蠕變時(shí)效狀態(tài)下，CA1試樣最大晶間腐蝕深度為180.6 μm，腐蝕等級(jí)為4級(jí)；CA2試樣最大晶間腐蝕深度為92.0 μm，腐蝕等級(jí)為3級(jí)。TEM結(jié)果表明：CA1試樣中以細(xì)小致密的θ′相為主，晶內(nèi)可見(jiàn)少量T1相；CA2試樣由于T1相在蠕變時(shí)效初期時(shí)存在析出優(yōu)勢(shì)，晶內(nèi)析出大量T1相的同時(shí)，伴隨著細(xì)小的θ′相，且CA2試樣T1相在亞晶界處的富集程度要低于CA1試樣的。
關(guān)鍵字: AL-Cu-Li合金；蠕變時(shí)效；力學(xué)性能；晶間腐蝕；T1相
（1. Light Alloy Research Institute, Central South University, Changsha 410083, China;
2. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
3. State Key Laboratory of High Performance and Complex Manufacturing, Central South University, Changsha 410083, China）
Abstract:The tensile properties and microstructure characteristics of Al-Cu-Li alloy during creep aging were studied by optical microscopy and transmission electron microscopy, tensile mechanical properties and Vickers hardness. The results show that the hardness and tensile strength increase gradually to the maximum, and then decrease slowly during creep aging. The maximum hardness and tensile strength are obtained after the CA2 sample (creep aging after 2% pre-stretching) creep aging for 16 h, which reaches the maximum values than CA1 sample (creep aging without pre-stretching) earlier about 4 h. When compared with CA1 samples in the creep aging, the peak value is sharper in the CA2 samples and possess higher hardness and tensile strength, but lower elongation. Under the condition of peak creep aging, the maximum intergranular corrosion depth of CA1 specimen is 180.6 μm, and the corrosion level is 4. The maximum intergranular corrosion depth of the CA2 specimen is 92.0 μm and the corrosion level is 3. TEM results show that the CA1 sample is dominated by small, dense θ′ phases, and a small amount of T1 phases can be seen in the crystal. For the sake with a precipitation advantage at the initial stage in the CA2 sample, a large number of T1 phases are precipitated in the crystal accompanying with a small θ′ phase, and the enrichment of precipitated T1 at the sub-crystal boundary is lower than that in the CA1 sample.
Key words: Al-Cu-Li alloy; creep aging; mechanical property; intergranular corrosion; T1 phase
