(1. 清華大學 新材料國際研發(fā)中心，北京 100084；
2. Ural State Pedagogical University, 26 Cosmonavtovst, Ekaterinburg 620017, Russia)
摘 要: 采用坩堝扭擺振動法測量了添加少量鈣的AZ91D鎂合金熔體的黏度，獲得了600~870 ℃溫度區(qū)間內升溫和降溫過程中的黏度—溫度關系曲線υ(t)和黏度—鈣添加量關系曲線υ(w)。結果表明：AZ91D鎂合金熔體的曲線υ(t)發(fā)生了不可逆轉變；曲線υ(t)發(fā)生轉折的溫度對鈣元素的添加量具有強烈依賴性，鈣添加量(質量分數(shù))為0.4%時，升溫和降溫過程的曲線υ(t)出現(xiàn)多溫度點的黏度值相符合現(xiàn)象；曲線υ(w)具有顯著的區(qū)間性特征，鈣添加量為0.7%~0.8%時，開始出現(xiàn)較多的新相。
關鍵字: 黏度；AZ91D鎂合金；鈣；Mg17Al12相；熔體結構轉變
small additions of calcium
（1. Advanced Materials International R&D Center, Tsinghua University, Beijing 100084, China;
2. Ural State Pedagogical University, 26 Cosmonavtovst, Ekaterinburg 620017, Russia）
Abstract:The method of crucible rotating oscillation damping was used for measurement of viscosity of the AZ91D magnesium alloy melt with small additions of calcium. The viscosity was measured in ascent and descent temperature interval from 600 ℃ to 870 ℃. The curves of melt viscosity versus temperature υ(t) with different calcium additions and the curves of melt viscosity versus calcium additions υ(w) at different temperatures were obtained. The results show that the υ(t) curve of AZ91D magnesium alloy melt has the phenomenon of irreversible transition. The temperature corresponding to the break point of υ(t) curve has dependence relation with addition of calcium. With calcium content (mass fraction) of 0.4%, the υ(t) curves of ascent temperature and descent temperature process have the same viscosity at many temperature points. The υ(w) curve presents interzone characteristic and new phases appear with the calcium content of 0.7%−0.8%.
Key words: viscosity; AZ91D magnesium alloy; calcium; Mg17Al12 phase; melt structure transition
