通过分析固溶态Cu-Ni-Si合金时效过程中导电率的变化,根据导电率与新相析出量之间的关系计算时效过程中新相的转变比率,在此基础上,确定不同温度下描述时效析出相转变比率与时效时间的Avrami相变动力学经验方程和导电率随时间变化的导电率方程,绘制出动力学“S”曲线,并且用固态热分解反应机理的积分方程验证用Avrami经验方程来描述合金的析出过程的正确性。对Cu—Ni-Si合金在500℃时效8h后的析出相进行选区电子衍射花样标定,发现析出相为δ-Ni2Si和β-Ni3Si。
The transformation ratio of new phase in Cu-Ni-Si alloy was calculated in terms of analyzing the electrical conductivity variations and the relationship between the electrical conductivity and the quantity of new phase. Both the Avrami phase transformation kinetics equation and the electrical conductivity equation changing with the aging time were derived at different temperatures, the transformation kinetics "S" curve was drawn. Then, though integral functions of the reactive mechanism of thermal decomposition of solid solution, the Avrami formulation for describing the kinetics of the phase transformation is proved to be correct. The precipitates are δ-Ni2Si and β-Ni3Si phases by indexing the selected field diffraction pattern of precipitates of Cu-Ni-Si alloy aging at 500 ℃ for 8 h.