Er微合金化对1441铝锂合金微观组织和力学性能的影响

Microstructures and Mechanical Properties of 1441 Al-Li Alloy with Er Micro-Alloying

采用铸锭冶金法制备了不同含量稀土元素Er的Al-Cu-Li合金。利用拉伸力学性能测试、扫描电子显微镜(SEM)、透射电子显微镜(TEM)及元素能谱分析(EDS)等分析测试手段,研究了Er的添加对Al-Cu-Li合金T8时效状态下的微观组织和力学性能影响。结果表明,合金在峰时效下的强度较未添加Er元素的Al-Cu-Li合金略有下降,添加0.3%Er(质量分数)的Al-Cu-Li合金的T8态峰时效屈服和抗拉强度均下降了30 MPa;添加Er元素的Al-Cu-Li合金的主要强化相仍然为δ'相(Al3Li)及S'相(Al2Cu Mg),Al-Cu-Li合金的Er元素未影响其时效析出响应速度;添加Er微合金化合金峰时效下内部有大量的δ'相和少量的S'相,而未添加Er元素的Al-Cu-Li合金峰时效下有大量的δ'相和大量的S'相,添加Er元素使峰时效态下S'相数量减少;Al-Cu-Li合金从始至终没有发现Al3Er强化相的存在证据;添加稀土元素Er,在凝固态时即可形成Al8Cu4Er相粒子,这些粒子直至均匀化和固溶热处理时仍未完全溶解于固溶体中;断口形貌分析显示添加Er元素使Al-Cu-Li合金的沿晶脆性断裂倾向增大,佐证了合金强度下降的力学性能表现。

Al-Cu-Li alloys containing different contents of Er were prepared by cast metallurgy. The effect of trace Er on mechanical properties and mierostructures of Al-Cu-Li alloy was examined with tensile properties measurement, scanning electron microscope （SEM）, transmission electron microscope （TEM） and energy dispersive spectroscopy （EDS）. The result showed that the addition of Er to A1-Cu-Li alloy decreased the strength marginally, and yield strength and tensile strength of the T8 alloy under peak.aging condi- tion were both declined by 30 MPa when the content of Er was 0.4% （mass fraction）. The aging precipitates in Er micro-alloyed AI- Cu-Li alloy were still 8＇（ Al3 Li） and S＇（A12 CuMg） phases, and the aging response was same with other alloys. The number of the 8＇ phase in the peak-aging alloy remained the same with Er addition increasing, while the number of S＇ phase decreased with Er addition increasing. However, there was no Al3Er phase in the Er-added A1-Cu-Li alloy from the start to the end. During solidification process, A18 Cu4 Er particles formed due to Er addition, which was not completely dissolved into the solid solution during homogenization and so- lution treatment. The possibility of intergranular brittle rupture grew with Er-added alloy indicated by fractography analysis technology, which proved the decrease of mechanical properties.