(上海交通大學(xué) 輕合金精密成型國家工程研究中心，上海200030)
摘 要: 研究擠壓態(tài)和等通道角擠壓(ECAE)態(tài)AZ31鎂合金的變形行為與微觀組織的相關(guān)性。結(jié)果表明，ECAE態(tài)AZ31鎂合金的室溫拉伸屈服強(qiáng)度與晶粒尺寸之間表現(xiàn)出反Hall-Petch關(guān)系，且拉壓不對(duì)稱性明顯減弱；在室溫壓縮時(shí)表現(xiàn)出應(yīng)變速率敏感性，并隨變形溫度升高，應(yīng)變速率敏感性因子變大。擠壓態(tài)合金的晶粒度為20 mm，具有典型的擠壓絲織構(gòu)，主要變形方式為基面位錯(cuò)滑移和孿生，導(dǎo)致了合金中明顯的拉壓不對(duì)稱性。ECAE態(tài)合金平均晶粒尺寸約為2 mm，織構(gòu)相對(duì)隨機(jī)化，導(dǎo)致合金壓縮時(shí)孿生比率明顯下降，其他變形模式比率增加，提高了變形抗力，降低了拉壓不對(duì)稱性。ECAE態(tài)AZ31鎂合金壓縮的激活能接近其晶界擴(kuò)散激活能，晶界滑移在一定程度上導(dǎo)致了合金的反Hall-Petch關(guān)系的出現(xiàn)以及應(yīng)變速率敏感性的增強(qiáng)。
關(guān)鍵字: AZ31鎂合金；等通道角擠壓；變形行為；拉壓不對(duì)稱性；應(yīng)變速率敏感性
equal channel angular extrusion
（National Engineering Research Center of Light Alloy Net Forming, Shanghai Jiao Tong University,
Shanghai 200030, China）
Abstract: The correlation between the microstructure and the deformation behavior of AZ31 alloys processed by as-extrusion and equal channel angular extrusion (ECAE) was investigated. The results show that there is a reverse Hall-Petch relationship between the yield stress and the grain size of ECAE AZ31 Mg alloy, and the tension-compression asymmetry is weakened; ECAE alloy also exhibits a strain rate sensitivity, and the strain rate sensitivity factor will be increased with increasing the process temperature. The average grain size is 20 μm for the as-extruded alloy with a typical ring basal texture, and the main deformation models at room temperature are basal slip and twinning, which result in the strong tension-compression asymmetry. The average grain size is about 2 μm for ECAE Mg alloy with a texture randomized relatively, which results in remarkably a decrease of twin volume fraction under compression loading, and then the tension-compression asymmetry in ECAE AZ31 alloy is weakened. The calculated apparent activation energy in the ECAE Mg AZ31 is approached to the activation energy of grain boundary diffusion Mg alloy, which provides an evidence to support that the deformation on grain boundaries plays an important role on the deformation behavior, and the possible grain boundary sliding (GBS) has contribution to the reverse Hall-Petch relationship and strain rate sensitivity in ECAE Mg alloy.
Key words: AZ31 Mg alloy; equal channel angular extrusion (ECAE); deformation behavior; tension-compression asymmetry; strain rate sensitivity
