本文用阳极溶解计时电位法,对稀土金属La在液态Al-Si合金中的扩散系数进行了测定。结果表明,973K,La浓度18.0×10~(-4)mol·cm~(-3)时,La在Al-5.2wt-％Si合金液中的扩散系数平均值DLa(Al-SI)=(0.91±0.01)×10~(-5)cm~2·S~(-1)。在953-1053K温度范围内,求得La在合金液中的扩散系数与温度间存在下列关系: lgDLa(Al-SI)=-1.78×10~(-3)-4909/T同时求得扩散激活能Q=94.00kJ·mol~(-1)。为了便于分析比较,对Sr在某些条件下的扩散系数也进行了测试。通过La,Sr扩散数据的比较,分析了变质元素的扩散对变质过程中出现的潜伏期,临界冷却速度等问题的影响。
The diffusion coefficients of La in liquid Al-Si alloy have been mea-sured successfully with anodic chronopotentiometry. At 973K the diffusion coef-ficient of La in liquid Al-5.2-wt%Si alloy D(L_La(Al-s?)) equals (0.91±0.01)×10~(-5)cm.s~(-1). In the range of temperature 953--1053K, the relationship between diffusioncoefficients and temperature is represented by lgD_(La(Al-Sl))=-1.78×10~(-3)-4909/T.The activation energy Q=94.00kJ.mol~(-1). Using the diffuaion data of La, Sr, the in-fluence of the diffusion of modificator on the incubation period of modificationeffect and critical cooling rate has been discussed.
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