铈对Al-Cu-Mg-Mn-Ag合金时效析出与显微组织的影响

Effect of cerium addition on precipitation and microstructure of Al-Cu-Mg-Mn-Ag alloys

通过铸锭冶金及形变热处理,制备了不同铈含量的Al-Cu-Mg-Mn-Ag合金。采用金相观察、差热分析、扫描电镜及透射电镜研究了添加铈对合金的时效析出过程及显微组织的影响。结果表明:添加铈能显著细化铸态合金的晶粒,使平均晶粒尺寸由93μm减小至30μm,还可以加速挤压态合金的时效硬化过程,提高硬化水平,使最大硬度提高10%以上;此外,添加铈可缩短合金的峰时效时间,降低主要强化析出相—Ω相的析出温度,同时,也降低?相的直径,提高其析出体积分数及其在200～300℃时的高温热稳定性。

Al-Cu-Mg-Mn-Ag alloys with different cerium contents were prepared by ingot metallurgy and thermomechanical treatment. The effect of cerium addition on the precipitation and microstructure of alloys was investigated by optical microscopy, differential scanning calorimetry, scanning electron microscopy and transmission electron microscopy. The results show that the cerium addition refines the grains of casting alloys and the average grain size decreases from 93 gm to 30 μm. Trace element cerium addition accelerates the aging hardening process of extruded alloys, increases the maximum hardness of alloys by about 10%, and decreases the precipitation temperature of Ω phase. Moreover, the addition of Ce into AI-Cu-Mg-Mn-Ag alloy decreases the size of Ω phase, and improves the density and thermal stability of Ω phase between 200 ℃and 300 ℃.