Mg-Al-M合金中Al-M相(M=Sr,Nd)析出行为的热力学分析

THERMODYNAMIC ANALYSIS OF THE PRECIPITATION BEHAVIORS OF Al-M(M=Sr, Nd) PHASES IN Mg-Al-M ALLOYS

以Al-M(M=Sr,Nd)二元相图、Miedema生成热模型和Toop模型为基础,建立了Mg-Al-M三元合金熔体中Al-M金属间化合物析出行为的热力学计算模型,并采用该模型对Mg-8Al-3．5Sr熔体中Al-Sr金属间化合物的析出温度进行了计算,结果与文献基本吻合．利用该模型对一定温度下Mg-9／6Al-M(M=Sr,Nd)熔体中优先析出Al-M金属间化合物所需M的最低含量进行了计算．根据计算结果,对Al-M金属间化合物在Mg-9／6Al-M合金熔体中的析出行为以及对合金力学性能可能的影响进行了分析和比较,提出了采用稀土Nd和碱土Sr复合添加来制备耐热镁合金的思路．

Based on the binary phase diagrams of Al-M（M=Sr, Nd）, Miedema model and Toop model, the thermodynamic calculation model for predicting the precipitation behaviors of the Al-M intermetallic compounds in Mg-Al-M system was deduced. The calculated precipitating temperature of Al-Sr compound in Mg-SA1-3.5Sr ternary system is in good agreement with the references. The lowest contents of M in the Mg-9/6Al-M（M=Sr, Nd）, making the Al-M compounds precipitate prior to α-Mg, were calculated, the precipitation behaviors of the Al-M compounds and their effects to the mechanical properties of Mg alloys were discussed. Composite addition of Nd and Sr to prepare the heat resistance of Mg alloys with higher strength was proposed.