【摘要】 采用显微组织观察和拉伸实验研究稀土金属（RE）添加对Al-12%Si-4%Cu-1.6%Mn耐热合金凝固过程和高温强度的影响。在加入RE的合金中观察到大量细小针状富RE相,固溶处理不能改变其形态与大小,表明其具有良好的热稳定性。RE的加入已完全改变共晶CuAl₂相的凝固过程,从偏聚在最终共晶晶粒边界上的网络状变成离散的块状,生长在如头发丝的富RE细针上。在含有Ce的合金中,块状CuAl2、颗粒状Al₁₅Mn3_Si₂和针状富RE相共生在一起;然而,在仅加入La的合金中,此共生现象并未发生。RE的加入不能显著改善合金的高温强度。而针状富RE相的形成也未显著改变合金拉伸过程中微裂纹的萌生与扩展。更多还原

【Abstract】 The effect of RE addition on solidification process and high-temperature strength of Al-12%Si-4%Cu-1.6%Mn（in wt.%）heat-resistant alloy was investigated by microstructure observation and tensile test.A great number of fine needle-like RE-rich phases are observed in the alloys with RE addition. Solutionizing treatment does not change their morphologies and sizes, indicating that they have good thermal stability. The addition of RE totally alters the solidification process of eutectic CruAl₂ phase, from network-like phase in the form of segregation at the final eutectic grain boundaries to discretely blocky phase growing on the hair-filamentous RE-rich needles. In the alloys with Ce addition, blocky CuAl₂, particulate Al₁₅Mn3_Si₂ and needle-like RE-rich needle phases grow together, but they did not occur in the alloy with only La addition. The addition of RE does not considerably improve the strength of the alloy at high temperatures. The formation of RE-rich phases also does not significantly alter the originating and propagating of micro-cracks in the alloy during tensile test.更多还原