(辽宁科技大学 材料与冶金学院，鞍山 114051)
摘 要: 研究粗晶粒Mg-2Al(质量分数，%)合金板材的高温拉伸性能和变形机制，并研究溶质Al原子对高温变形机制的影响。通过熔炼、浇铸、轧制和热处理等方法制备平均晶粒尺寸为48.35 μm的Mg-2Al (质量分数，%)板材。在300~450 ℃条件下，以恒定拉伸速率1×10-3 s-1和1×10-2 s-1进行拉伸至失效实验，并在4.98×10-5~ 2.02×10-2 s-1的应变速率范围内进行应变速率变化条件下的拉伸实验。结果表明，纯Mg的应力指数(n)较为稳定，n ≈ 5时，变形机制为位错攀移蠕变。Mg-2Al合金的应力指数呈现3个区域。在高温和低应变速率区域，Mg-2Al呈现出溶质牵制位错蠕变的特征，即应力指数为n ≈ 3.83，蠕变激活能为Q≈141.46 kJ/mol，且当拉伸速率为1×10-3 s-1时，Mg-2Al合金在400和450 ℃的伸长率均超过100%。
关键字: Mg-2Al合金；粗晶粒；应力指数；激活能；蠕变
（School of Materials Science and Metallurgy, University of Science and Technology Liaoning, Anshan 114051, China）
Abstract:High temperature tensile properties and deformation mechanisms of coarse grained Mg-2Al (mass fraction, %) alloy were investigated, and the effects of solute Al on the deformation mechanism were investigated. The Mg-2Al plate with an average grain size of 48.35 μm was made by smelting, casting, hot rolling and heat treatment. Under temperatures from 300 ℃ to 450 ℃, elongation-to-failure tests were conducted under constant tensile rates of 1×10-3 and 1×10-2 s-1, and strain-rate-change tests were conducted under varying strain rates from 4.98×10-5 to 2.02×10-2 s-1. The results show that the deformation mechanism of pure Mg is dislocation climb creep with a stable stress exponent of n≈5. Mg-2Al alloy exhibits three regions with varying stress exponents. In the region of high temperature and low strain rate, Mg-2Al alloy exhibits characteristics of solute-drag creep with n≈3.83 and an activation energy of 141.46 kJ/mol. Tensile ductility of over 100% are consistently achieved for the Mg-2Al alloy when deformed at high temperatures of 400 ℃ and 450 ℃ and low strain rate of 1×10-3 s-1.
Key words: Mg-2Al alloy; coarse grain; stress exponent; activation energy; creep
