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通过扫描电镜观察、XRD物相定性分析,研究了Al-4Cu-Mg-Er合金相组成及其均匀化制度。结果表明:Er元素主要以Al8Cu4Er相形式存在于铸态合金中;Al8Cu4Er相与Al2Cu相在合金铸态组织中共生于晶界,形成典型的枝晶偏析;Al8Cu4Er相在合金晶界凝固时比Al2Cu相优先析出,生长为典型的枝晶组织。与Al2Cu相相比较,Al8Cu4Er相的熔点较高,为难溶相,成为该合金均匀化制度的制约因素。经400℃×6h+495℃×24h均匀化处理后,Al8Cu4Er相回溶至基体,合金晶界变薄,均匀化效果明显。
The phase composition and homogenization of Al-4Cu-Mg-Er alloy were investigated by scanning electron microscopy and XRD. The results show that the Er element mainly exists in as-cast alloy in the form of Al8Cu4Er phase. Al8Cu4Er phase and Al2Cu phase coexist in the as-cast alloy in the grain boundary, forming typical dendritic segregation. When Al8Cu4Er phase solidifies in the alloy grain boundary, Precipitation phase priority, growth as a typical dendritic tissue. Compared with Al2Cu phase, Al8Cu4Er phase has a higher melting point and is a poorly soluble phase, which becomes a limiting factor in the homogenization regime of the alloy. After being homogenized at 400 ℃ for 6h and 495 ℃ for 24h, Al8Cu4Er phase was dissolved back into the matrix, the grain boundary became thinner and the homogenization effect was obvious.