机械合金化制备具有纳米相复合结构的Al-Pb互不溶体系中Pb相的粗化动力学和添加Cu对其粗化的影响

利用X射线衍射仪、扫描电子显微镜和透射电子显微镜研究了机械合金化制备的具有纳米相复合结构的Al-Pb互不溶体系中Pb相的粗化动力学和添加Cu对其粗化的影响。结果表明在573、623、673和723 K退火不同时间后,尽管Al-Pb纳米相复合结构合金中组成相的尺寸均在纳米量级,Pb相的平均颗粒尺寸与退火时间之间仍满足三次方定律。Pb相的粗化激活能为84.80 kJ/mol,此值接近于基体Al的晶界自扩散激活能。这表明Pb相的粗化受晶界扩散控制。添加Cu降低了Pb相的粗化速率,这与Cu在Al和Pb相的界面偏聚,降低了Al/Pb的界面能有关。添加Cu后,Pb相的长大激活能增加。

Coarsening kinetics of Pb phase in a nanocomposite alloy produced by mechanical alloying in immiscible Al-Pb system and the influence of Cu addition on it

Coarsening kinetics of Pb phase in a nanocomposite alloy produced by mechanical alloying in immiscible Al-Pb system and the influence of Cu addition on it have been studied by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The results show that when annealing at 573, 623, 673 and 723 K for different times, the relation of average particle size of Pb phase in Al-Pb nanocomposite alloys to time obeys the cube law even though the size of the constituent phase is in the nanometer range. The coarsening activation energy of Pb phase is 84.80 kJ/mol, close to the grain boundary self-diffusion activation energy of Al matrix. This indicates that the coarsening of Pb phase is controlled by grain boundary diffusion. Adding Cu decreases the coarsening rate of Pb phase, primarily by reducing the interfacial energy through Cu segregation at the Al/Pb interface. The coarsening activation energy of Pb phase is increased by the addition of Cu.