(沈陽工業(yè)大學(xué) 材料科學(xué)與工程學(xué)院，沈陽 110178)
摘 要: 采用分離式Hopkinson桿在應(yīng)變速率為496~2 120 s−1范圍對擠壓態(tài)AZ31B鎂合金進(jìn)行了高速沖擊壓縮實(shí)驗(yàn)，并采用金相顯微鏡對壓縮后鎂合金的組織演變規(guī)律進(jìn)行研究。結(jié)果表明：在不同應(yīng)變速率下變形時(shí)，擠壓態(tài)AZ31鎂合金的應(yīng)力—應(yīng)變曲線幾乎重合，說明AZ31B鎂合金的應(yīng)力對應(yīng)變速率不敏感；但其顯微組織變化對應(yīng)變速率非常敏感，當(dāng)變形速率較低時(shí)，其組織幾乎全部由孿晶組成；當(dāng)應(yīng)變速率增加時(shí)，孿晶數(shù)量減少；在應(yīng)變速率相對較低時(shí)(496 s−1)，鎂合金變形主要以孿生方式進(jìn)行；當(dāng)應(yīng)變速率較高時(shí)(2 120 s−1)，除孿晶變形之外，柱面滑移和錐面滑移也可能啟動以協(xié)調(diào)變形。
關(guān)鍵字: 鎂合金；高應(yīng)變速率；變形組織；變形機(jī)制；孿生
high strain rate compression
（School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110178, China）
Abstract: In order to investigate the microstructure evolution under high strain rate deformation, extruded AZ31B magnesium alloy was impacted by split Hopkinson compression bars at the strain rates of 496−2 120 s−1. The microstructures of the specimens were observed by optical microscopy. The results show that the stress—strain curves of AZ31B magnesium alloy are almost overlap under different strain rates, implying that the stress of AZ31B magnesium is not sensitive to the strain rate. The deformation microstructure analysis demonstrates that the microstructure is sensitive to the strain rate. When the strain rate is relatively low, the microstructure is dominated by intense twinning. With increasing strain rate, the volume fraction of twinning decreases. The microstructure analysis demonstrate that at relatively low strain rate, the deformation mechanism of AZ31B magnesium alloy under impact load is twinning, while the strain rate increases to 2 120 s−1, the prismatic slip and pyramidal slip may be active to accommodate with the deformation except twinning.
Key words: AZ31B magnesium alloy; high strain rate; deformation microstructure; deformation mechanism; twinning
