摘要
研究了8090Al-Li 合金在缓慢冷却时的凝固过程,结果表明:L→α-Al+L′反应是基本凝固过程,贯彻始终。由于溶质元素 Cu 的严重偏析,使得合金终凝固温度显著降低,凝固温度区间扩大,终凝温度在525℃左右,但熔体的90%以上在635—590℃之间凝固,在最后凝固区溶质大量富集,从而形成了 T_2相等低熔点共晶化合物。杂质元素 Fe,Si 具有强烈偏析倾向。在缓冷过程中,形成粗大的 Al_3Fe,AlLiSi,Al_7Cu_2Fe 等金属间化合物。
The solidification and segregation behaviors of 8090 Al-Li alloy have been in-vestigated with differential thermal analysis and metallographic-electron microprobe method.The results show that the reaction of L→α-Al+L' is a essential solidification process and goeson to termination.During solidification,Cu segregates to the interdendrite and finally formsα-Al+T_2 eutectie.As a result,the solidification temperature range is greatly extended.Morethan 95% molten solidifies in the temperature range of 635—590℃ and the solidification pro-cess terminates at about 525℃.The impure elements Fe and Si have a strong segregationtendeney and form the insoluble constituents Al_3Fe,Al_7Cu_2Fe,AlLiSi,etc.in the finally solidi-fied zone when slow solidification.
关键词
合金
凝固
偏析
锂
铝
Al-Li alloy
solidification
solute segregation
as-cast microstucrure
