采用显微硬度、电导率测试、扫描电镜及三维原子探针等测试手段研究了Al-Zr-Yb、Al-Zr-Si和Al-Zr-Si-Yb合金的时效析出行为以及Yb和Si的作用机制.结果表明,同时添加Yb和Si能明显提高Al-Zr合金的析出强化性能,两者均可加速Al-Zr合金时效析出,但作用机制不同.时效初期Yb在α-Al中优先扩散,形成Al3Yb作为Zr析出的异质核心,加速Zr的析出,形成核壳结构的复合析出相Al3(Zr1-xYbx).Si可以提高Zr在Al基体中的扩散速率,因此添加Si后合金中Al3Zr的时效析出孕育期缩短,析出相长大速率增大,但同时合金抗粗化能力下降.此外,Si的加入大大降低了Yb在Al基体中的固溶度.因此尽管Yb仍然倾向于偏聚在析出相中心,但原子分数仅约1％,Zr在析出相中几乎均匀分布,Si在基体/析出相界面处略有偏聚,析出相(Al,Si)3(Zr1-xYbx)总体上不呈现核壳结构.
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