(中南大學(xué) 材料科學(xué)與工程學(xué)院， 長沙 410083)
摘 要: 采用GLEEBLE-1500熱模擬機對Mg-Gd-Y-Zr稀土鎂合金在溫度為300~500 ℃、 應(yīng)變速率為0.000 1~1.0 s-1、最大變形程度為50%的條件下， 進行了恒應(yīng)變速率高溫壓縮模擬實驗研究， 分析了實驗合金高溫變形時流變應(yīng)力與應(yīng)變速率及變形溫度之間的關(guān)系以及組織變化，計算了塑性變形表觀激活能及相應(yīng)的應(yīng)力指數(shù)， 為選擇這種合金的熱變形加工條件提供實驗依據(jù)。 結(jié)果表明： 合金的穩(wěn)態(tài)流變應(yīng)力隨應(yīng)變速率的增大而增大, 在恒應(yīng)變速率條件下， 合金的真應(yīng)力水平隨溫度的升高而降低； 在給定的變形條件下， 計算得出的塑性變形表觀激活能和應(yīng)力指數(shù)分別為260 kJ/mol和5.6。 根據(jù)實驗分析， 合金的熱加工宜在400~500 ℃溫度范圍內(nèi)進行。
關(guān)鍵字: 稀土鎂合金； 熱變形； 變形激活能； 力學(xué)性能
XIAO Yang, JIANG Hao
（School of Materials Science and Engineering,
Central South University, Changsha 410083, China）
Abstract: The stress-strain relation of Mg-8.75%Gd-3.82%Y-0.54%Zr (mass fraction,%) alloy was investigated. The test was carried out in the strain rate range of 0.000 1-1.0 s-1, in the temperature range of 300-500 ℃ and at maximum strain of 50% on hot-simulation machine GLEEBLE-1500. The relation between true stress, true strain and that between deformation temperature and microstructures of the tested alloy were studied during hot-compression. The apparent deformation activation energy and corresponding stress exponent under hot-compression evaluated quantitatively. The results may lay the foundation for selecting hot deformation conditions of the alloy. The relation between stress and strain is obviously affected by strain rate and deformation temperature. The steady flow stress becomes higher with increase of strain rate at constant temperature, and lowers with increase of deformation temperature at constant strain rate. The apparent deformation activation energy increases markedly in the range of 400-500 ℃, no more changes in the range of 300-400 ℃. The apparent activation energy 260 kJ/mol and the corresponding stress exponent 5.6 were determined respectively. The temperature range of 400-500 ℃ is suggested for hot deformation of this alloy.
Key words: rare earth magnesium alloy; hot deformation; deformation activation energy; mechanical properties
