激光立体成形AlSi10Mg合金的微观组织及力学性能

Microstructure and Mechanical Property of AlSi10Mg Alloy Prepared by Laser Solid Forming

激光立体成形已逐渐成为大型高性能复杂铝合金构件制造的一条重要途径。采用具有不同波长的CO_2和YAG激光器在铸态基材上进行了AlSi10Mg合金的激光立体成形,研究了不同激光器对AlSi10Mg合金沉积态和T6热处理态下的微观组织和力学性能的影响。利用XRD、OM和SEM研究了AlSi10Mg合金成形件的微观组织;利用电子拉力试验机测试了AlSi10Mg合金成形件的力学性能。结果表明:相比铸态基材,AlSi10Mg合金沉积态组织主要由<100>取向沿沉积方向外延生长的柱状α-Al枝晶和枝晶间呈纤维或颗粒状生长的Al-Si共晶组成,组织显著细化;且在530℃,3~5 min固溶处理后可实现共晶Si的球化。与CO_2激光相比,采用更短波长的YAG激光进行成形时组织更为细化。经T6热处理后,采用YAG激光成形的AlSi10Mg合金力学性能明显优于压铸铝合金。

Laser solid forming（LSF） has gradually become an important way to manufacture large-scale high-performance complex aluminum alloy components. AlSi10 Mg alloy was deposited on the as-cast substrate by LSF using CO_2 and YAG lasers respectively. The effects of laser type on the microstructure and mechanical properties of AlSi10 Mg alloy deposits in asdeposited and T6 heat treated states were investigated. XRD, OM and SEM were used to study the microstructures of these deposits, and tensile test was performed to measure their mechanical properties. Results show that the as-deposited microstructure of AlSi10 Mg alloy mainly consists of the columnar α-Aldendrites epitaxially grown with the 100 orientation along the deposition direction and Al-Si eutectic in the inter-dendritic with the fiber or particle shape. Compared with the ascast microstructure, these microstructure are refined remarkably, and the spheroidization of eutectic Si can be achieved only3-5 min in solution treatment at 530 ℃, which is also much shorter than that for the as-cast microstructure. Compared with CO_2 laser, the more refined microstructure are obtained in LSF using YAG laser with the shorter wevelength. After T6 treatment, the mechanical properties of AlSi10 Mg alloy prepared by YAG laser are obviously better than those of die-cast aluminum alloy.