(1. 清华大学 新材料国际研发中心，北京 100084；
2. Ural State Pedagogical University, 26 Cosmonavtovst, Ekaterinburg 620017, Russia)
摘 要: 采用坩埚扭摆振动法测量了添加少量钙的AZ91D镁合金熔体的黏度，获得了600~870 ℃温度区间内升温和降温过程中的黏度—温度关系曲线υ(t)和黏度—钙添加量关系曲线υ(w)。结果表明：AZ91D镁合金熔体的曲线υ(t)发生了不可逆转变；曲线υ(t)发生转折的温度对钙元素的添加量具有强烈依赖性，钙添加量(质量分数)为0.4%时，升温和降温过程的曲线υ(t)出现多温度点的黏度值相符合现象；曲线υ(w)具有显著的区间性特征，钙添加量为0.7%~0.8%时，开始出现较多的新相。
关键字: 黏度；AZ91D镁合金；钙；Mg17Al12相；熔体结构转变
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
