用电子探针测定铝合金在定向凝固过程中的溶质分配系数

Characterization of Solute Distribution Coefficient in Aluminum Alloys during Directional Solidification by EPMA

中文关键词:  铝合金  定向凝固  液固界面  溶质分配系数  电子探针

英文关键词:aluminum alloy  directionally solidification  liquid-solid interface  solute distribution coefficient  electron microprobe

中文摘要:

      用电子探针测定了铝合金中Al-1.35%Cu和Al-0.25%Cr在定向凝固过程中液固界面处的溶质分配系数.结果表明:液相区的Cu含量随离开界面的距离呈指数衰减,而固相区的则呈线性衰减.液固界面层厚度约在5～7μm范围内.凝固速度越快,凝固初始过渡区就越短.对于平衡分配系数小于1的Al-1.35%Cu铝合金,非平衡分配系数大于平衡分配系数;而对于平衡分配系数大于1的Al-0.25%Cr铝合金,非平衡分配系数则小于平衡分配系数;且平衡分配系数与非平衡分配系数的这种差别随凝固速度的加快而显着增大.

英文摘要:

      The electron microprobe was used to determine the solute distribution coefficient at liquid-solid interface in Al-1.35%Cu and Al-0.25%Cr alloys during directionally solidification.It has been shown that the content of Cu decreased exponentially in liquid zone and linearly in solid zone with the distance from the interface.The thickness of the liquid-solid interface is about 5～7μm,the larger is the solidification rate,the shorter is the initial transition zone of solidifition.For Al-1.35%Cu alloy,the equilibrium solute distribution coefficient k₀ less than 1 and its non-equilibrium solute distribution coefficient k is larger than k₀.For Al-0.25%Cr,k₀ is more than 1 and k is less than k₀.The difference between k and k₀ is greatly increased with the increase of the solidfication rate.