(湖南大學(xué) 材料科學(xué)與工程學(xué)院，長(zhǎng)沙 410082)
摘 要: 研究AZ31鎂合金軋制板材在低溫(室溫至423 K)拉伸條件下的力學(xué)性能，并通過高溫金相顯微鏡的拉伸附件觀察動(dòng)態(tài)微觀組織的變化過程。結(jié)果發(fā)現(xiàn)：鎂合金的塑性隨溫度的升高和應(yīng)變速率及負(fù)載的降低而增 加，表現(xiàn)出一定的應(yīng)變速率敏感性。常溫下的主要變形機(jī)制為{1110}壓縮孿生，其形核和長(zhǎng)大速度很快，但同時(shí)也存在少量的基面滑移，不同類型的孿晶在晶粒中彼此相交；而隨著溫度的升高，a+c非基面滑移的臨界剪切應(yīng)力迅速下降，大量非基面滑移系被激發(fā)，板材塑性性能明顯改善；當(dāng)應(yīng)變速率較高時(shí)(423 K，應(yīng)變速率10−2 /s)，斷裂方式為有一定塑性特征的解理形貌；隨著應(yīng)變速率的降低(423 K，應(yīng)變速率10−3 /s)，斷裂方式逐漸變?yōu)樗苄詳嗔选?/FONT>
關(guān)鍵字: 鎂合金；壓縮孿晶；基面滑移；變形行為；斷裂機(jī)制
（School of Materials Science and Engineering, Hunan University, Changsha 410082, China）
Abstract:The mechanical behavior and dynamic microstructural evolution of hot-rolled AZ31 Mg alloy were studied by tensile attachment of high-temperature microscopy (HTM) at different temperatures from room temperature (RT) to 423 K. The results show that the ductility of Mg alloy material increases with the increase of deformation temperature and the decreases of load and strain rate and has certain strain rate sensitivity. The main deformation evolution is {1110} contraction twinning at RT which has high nucleation rate and growth velocity and little basal slips. Different types of twins can intersect with each other and results in severe shear in the existing twin. With the increase of temperature, the critical resolved shear stress (CRSS) of a+c non-basal slip is surpassed easily, a great many non-basal slip systems are activated and the plastic property of Mg alloy is improved obviously. At 423 K, when the strain rate is 10−2 /s, the alloy exhibits ductile fracture with dimples. With the decrease of strain rate (10−3 /s), the fracture transfer plastic deformation step by step.
Key words: magnesium alloys; contraction twin; basal slip; deformation behavior; fracture mechanism
