(沈陽工業(yè)大學 材料科學與工程學院，沈陽 110870)
摘 要: 采用分離式霍普金森拉桿及壓桿裝置，研究擠壓態(tài)AZ31鎂合金高速變形下的各向異性及拉壓不對稱性，并從微觀變形機制的角度探討具有強烈初始基面織構(gòu)的擠壓態(tài)鎂合金各向異性及拉壓不對稱性產(chǎn)生的原因。結(jié)果表明：在高速變形條件下，依據(jù)加載方向及應(yīng)力狀態(tài)擠壓態(tài)AZ31鎂合金的拉伸行為表現(xiàn)出很強的各向異性，但壓縮行為的各向異性不明顯；在擠壓方向表現(xiàn)出很強的拉壓不對稱性，而在垂直于擠壓方向的拉壓不對稱性很低。擠壓態(tài)AZ31鎂合金宏觀上的各向異性及拉壓不對稱性是由于不同的微觀變形機制所引起的。沿擠壓方向拉伸的主要變形機制為柱面滑移，沿垂直于擠壓方向拉伸及壓縮的主要變形機制為錐面滑移；沿擠壓方向壓縮時初始變形機制為拉伸孿晶，當變形量為0.08(8%)左右時由于孿晶消耗殆盡，變形變而以滑移的方式進行。
關(guān)鍵字: 鎂合金；各向異性；拉壓不對稱性；變形機制；高應(yīng)變速率
（School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110870, China）
Abstract:The anisotropy and asymmetry of an as-extruded AZ31 magnesium alloy deformed under high strain rate were investigated by split Hopkison tension (SHTB) and pressure bar (SHPB). The reasons for the anisotropy and asymmetry were analyzed in terms of deformation mechanisms. The tension and compression were conducted along the extrusion direction and transverse direction, respectively. The results demonstrate that the as-extruded AZ31 magnesium alloy exhibits pronounced anisotropy in tension, but the anisotropic behavior is not obvious in compression according to the loading direction and stress state. The anisotropy is considerably apparent rather in tension than in compression and the asymmetry is more pronounced in extrusion direction than in transverse direction. The anisotropy and asymmetry of the as-extruded magnesium alloy are caused by the variety of the deformation mechanisms: the prismatic slip is the main activation system if tension stress is along the extrusion direction, while the pyramidal slip is the control deformation mechanism for tension and compression along the transverse direction. The initial deformation mechanism of compression along the extrusion direction is the tension twinning; when the strain is about 0.08 (8%) the tension twinning is exhausted. At this time the main deformation mechanism is changed to be slipping.
Key words: magnesium alloy; anisotropy; tension compression asymmetry; deformation mechanism; high strain rate
