(沈陽(yáng)工業(yè)大學(xué) 材料科學(xué)與工程學(xué)院，遼寧省鎂合金及成形技術(shù)重點(diǎn)實(shí)驗(yàn)室，沈陽(yáng) 110870)
摘 要: 采用分離式霍普金森壓桿(SHPB)測(cè)試預(yù)孿晶AZ31鎂合金板材在應(yīng)變速率分別約為800、1200和1600 s-1時(shí)的動(dòng)態(tài)真應(yīng)力-真應(yīng)變曲線。通過(guò)自編程軟件及電子背散射衍射(EBSD)技術(shù)分析預(yù)孿晶試樣在高應(yīng)變速率前后微觀組織和織構(gòu)的演變。結(jié)果表明：沿橫向(TD)預(yù)壓縮后再沿著軋制方向(RD)復(fù)合預(yù)壓縮可促進(jìn)AZ31鎂合金板材中多孿晶變體及二次拉伸孿晶的激活。對(duì)于沿TD方向一次預(yù)壓縮的試樣，其法向(ND)高應(yīng)變速率下的屈服強(qiáng)度急劇下降，這主要是由于退孿生的啟動(dòng)。然而，對(duì)于沿TD+RD復(fù)合預(yù)壓縮試樣，由于 - 二次孿晶和大量交叉孿晶變體的形成可以有效抑制退孿生行為，一定程度上提高了AZ31鎂合金ND方向的屈服強(qiáng)度，并且拉伸孿晶的形成能夠便利于啟動(dòng)更多的滑移系，改善了鎂合金板材ND方向的塑形變形行為。
關(guān)鍵字: AZ31鎂合金；孿生；織構(gòu)；高應(yīng)變速率；變形機(jī)制
（School of Materials Science and Engineering, Key Laboratory of Magnesium Alloys and the Processing Technology of Liaoning Province, Shenyang University of Technology, Shenyang 110870, China）
Abstract:The high strain rates compressive behavior of AZ31 magnesium alloy sheet along ND was measured by split Hopkinson pressure bar (SHPB) at strain rates of 800, 1200 and 1600 s-1. The microstructure and texture evolution of pre-twinning samples, including prior and after high strain rates compressive deformation, were analyzed by electron back-scatter diffraction (EBSD) and self-made software. The results show that the pre-twinning AZ31 magnesium alloy sheet along transverse direction (TD) and then rolling direction (RD) can promote the activation of multiple twin variants and double twins. For the samples of pre-twinning along TD, the compressive yield strength along ND of high strain rates decreases due to the occurrence of de-twinning. However, for the samples of pre-twinning along TD then RD, the formation of - double twinning and a large number of cross-twins lamellas inhibit the de-twinning behavior and enhance the yield strength of magnesium alloy along ND. Further more, the formation of extension twinning contributes to initiate more slip systems and improves the deformation behavior of AZ31 magnesium sheet along ND.
Key words: AZ31 magnesium alloys; pre-twinning; texture; high strain rate; deformation mechanism
