(遼寧科技大學(xué) 材料與冶金學(xué)院，鞍山 114051)
摘 要: 研究粗晶粒Mg-2Al(質(zhì)量分?jǐn)?shù)，%)合金板材的高溫拉伸性能和變形機(jī)制，并研究溶質(zhì)Al原子對高溫變形機(jī)制的影響。通過熔煉、澆鑄、軋制和熱處理等方法制備平均晶粒尺寸為48.35 μm的Mg-2Al (質(zhì)量分?jǐn)?shù)，%)板材。在300~450 ℃條件下，以恒定拉伸速率1×10-3 s-1和1×10-2 s-1進(jìn)行拉伸至失效實(shí)驗(yàn)，并在4.98×10-5~ 2.02×10-2 s-1的應(yīng)變速率范圍內(nèi)進(jìn)行應(yīng)變速率變化條件下的拉伸實(shí)驗(yàn)。結(jié)果表明，純Mg的應(yīng)力指數(shù)(n)較為穩(wěn)定，n ≈ 5時(shí)，變形機(jī)制為位錯(cuò)攀移蠕變。Mg-2Al合金的應(yīng)力指數(shù)呈現(xiàn)3個(gè)區(qū)域。在高溫和低應(yīng)變速率區(qū)域，Mg-2Al呈現(xiàn)出溶質(zhì)牽制位錯(cuò)蠕變的特征，即應(yīng)力指數(shù)為n ≈ 3.83，蠕變激活能為Q≈141.46 kJ/mol，且當(dāng)拉伸速率為1×10-3 s-1時(shí)，Mg-2Al合金在400和450 ℃的伸長率均超過100%。
關(guān)鍵字: Mg-2Al合金；粗晶粒；應(yīng)力指數(shù)；激活能；蠕變
（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
