(中南大學(xué) 材料科學(xué)與工程學(xué)院，長(zhǎng)沙 410083)
摘 要: 通過(guò)光學(xué)顯微鏡、掃描電鏡、透射電鏡、電子背散射衍射以及硬度測(cè)試研究軋制變形速率對(duì)7050鋁合金微觀組織演變的影響，分析軋制變形速率影響合金淬火敏感性的微觀機(jī)理。結(jié)果表明：變形速率較小時(shí)(5 s−1和8 s−1)，合金再結(jié)晶分?jǐn)?shù)低，試樣中存在大量的亞組織結(jié)構(gòu)，亞晶粒的尺寸較小，晶界較難分辨，為小角度晶界，固溶慢速淬火的試樣中少量η平衡相在亞晶界上形核析出；隨著變形速率的增加，亞晶長(zhǎng)大，晶界平直逐漸向大角度晶界轉(zhuǎn)變，η平衡相在晶界上析出增加，在亞晶內(nèi)部亦有明顯析出；當(dāng)變形速率升高至15 s−1時(shí)，固溶后試樣的再結(jié)晶百分?jǐn)?shù)明顯增加，在大角度晶界處以及再結(jié)晶晶粒內(nèi)出現(xiàn)大量非均勻形核析出，同時(shí)，在亞晶區(qū)域觀察到較多析出，與微觀組織演變對(duì)應(yīng)，合金時(shí)效態(tài)硬度性能測(cè)試結(jié)果表明：隨著軋制變形速率增加，慢速淬火的試樣力學(xué)性能損失變大，合金淬火敏感性增加。
關(guān)鍵字: 7050鋁合金；軋制變形速率；淬火敏感性
quench sensitivity of 7050 aluminum alloy plate
（School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The optical microscopy, scanning electron microscopy, transmission electron microscopy, electron backscatter diffraction, hardness and electric conductivity measurements are employed to study the effect of deformation rate on the microstructure evolution and quench sensitivity of 7050 aluminum alloy. The results show that, the recrystallized fraction is very low with deformation rate at low level of 5 s−1 and 8 s−1. There are a large number of sub-structures in the samples and the average size of the sub-grains is quite small. The sub-grain boundary is hard to distinguish, which is called small-angle grain boundary, and a few equilibrium η phases mainly precipitates at these boundaries during air quenching after solution. With increasing the deformation rate, the sub-grains coarsen and the gradual boundary misorientation occurs, and more equilibrium η phase precipitates at the sub-grain boundary. Rolling at high deformation rate (15 s−1) can increase the recrystallized fraction seriously. The equilibrium phases precipitate at the high angle grain boundaries and inside the recrysatllized grains with high density. Meanwhile, some precipitates are also observed inside the sub-grains. Actually, the incoherent Al3Zr particles play a vital role in the precipitation of equilibrium η phase during air quench. The results of hardness and electric conductivity tests indicate that, with increasing the rolling rate, the loss of mechanical properties subject to the slow quenched samples increases, and the quench sensitivity of the alloy increases.
Key words: 7050 aluminum alloy; deformation rate; quench sensitivity
