微量钪对低Cu/Mg 比Al-Cu-Mg-Li 合金微观组织及性能的影响

通过时效硬化曲线的测量、室温拉伸实验以及时效组织的电镜观察, 研究了微量钪对低Cu/Mg 比Al-Cu-Mg-Li 合金时效行为、显微组织和力学性能的影响。实验结果表明, 微量钪的添加能显著增强该合金的时效硬化和强化效果, 但延长了合金达到时效峰值所需的时间。微观组织分析结果表明, 微量钪的添加影响了合金的时效析出过程, 在不含钪的Al-4.0Mg-1.5Cu-1.0Li-0.12Zr合金中, 时效析出相为沿位错大量析出、分布不均匀的S 相和少量的δ′相(Al₃Li)及Al₃Zr 粒子;而在含钪的合金中主要析出相为弥散细小的Al₃Li/ Al₃(Sc, Zr)复合相与δ′相。

Effects of Small Addition of Sc on Microstructure and Properties of Low Cu/Mg Ratio Al-Cu-Mg-Li Alloy

The effects of addition of a trace amount of Sc on the aging behaviour, microstructure and mechanical properties of low Cu/Mg ratio Al-Cu-Mg-Li alloy have been investigated by measurement of age hardening curves, room temperature tensile test and electron microscopic observation of aging structure.The test results indicate that a trace amount of Sc can improve markedly its age hardening and reinforcement, but delay its aging peaks.The results obtained by analysing its microstructure have shown that addition of a trace amount of Sc can affect the age precipitating process of the alloy.In the Sc-free Al alloy(Al-4.0Mg-1.5Cu-1.0Li-0.12Zr), the age precipitated phases are a large amount of S phase, a small amount of δ' (Al₃Li)and Al₃Zr particles, which are precipitated and distributed along the dislocation, whereas in the Sc-containing alloy(Al-4.0Mg-1.5Cu-1.0Li-0.2Sc-0.12Zr), main precipitated phases are finely dispersed Al₃Li/Al₃(Sc, Zr)compound particles and δ'.