挤压铸造与超声处理对铸造铝锂合金组织与性能的影响

Effect of Squeeze Casting and Ultrasonic Treatment on Microstructure and Properties of Cast Al-Li Alloy

目的研究挤压铸造与超声处理工艺对铸造铝锂合金组织与性能的影响规律,分析工艺改变对组织细化及性能提升的作用机理,解决传统重力铸造下铝锂合金性能较差的问题。方法将挤压铸造(SC)与超声处理(UT)相结合制备Al-2Li-2Cu-0.5Mg-0.2Zr合金,在熔体超声2min后,以50MPa的挤压力制备合金,探究各工艺对铸造铝锂合金显微组织与力学性能的影响。结果与传统的重力铸造(GC)相比,SC合金的孔隙率和成分偏析显著降低,晶粒尺寸也明显减小,特别是经过UT+SC处理的合金得到了进一步优化。经UT+SC处理后,Al-2Li-2Cu合金的极限抗拉强度(UTS)、屈服强度(YS)和伸长率分别为235MPa、135MPa和15%,与GC合金相比,分别提高了113.6%、28.6%、1150%,与SC合金相比,分别提高了5.4%、3.8%、15.4%。结论UT+SC工艺能明显提升铸造铝锂合金的性能。UT+SC制备的Al-Li合金的强度和伸长率的提高归因于孔隙率的降低、晶粒细化和第二相的均匀分布。将挤压铸造与超声处理相结合制备铸造铝锂合金解决了重力铸造下合金性能较差的问题,为满足航空航天要求的高强韧铸造铝锂合金的制备提供了一种行之有效的新方法。

The work aims to study the influence of squeeze casting and ultrasonic treatment on the microstructure and me-chanical properties of cast Al-Li alloy,and analyze the mechanism of the role of the process changing on the microstructure and property enhancement,so as to solve the poor performance of Al-Li alloy under the traditional gravity casting.Squeeze casting(SC)and ultrasonic treatment(UT)were combined to prepare Al-2Li-2Cu-0.5Mg-0.2Zr alloy.After melt ultrasonication for 2 min,the alloy was prepared at 50 MPa extrusion pressure,to explore the influence of each process on the microstructure and mechanical properties of cast Al-Li alloy.The results showed that compared with the traditional gravity casting(GC),the porosity and composition segregation of SC alloy were significantly reduced,and the grain size was also significantly re-duced,especially the UT+SC alloy was further optimized.After UT+SC,the ultimate tensile strength(UTS),yield strength(YS)and elongation of Al-Li alloy were 235 MPa,135 MPa and 15%respectively,which were 113.6%,28.6%and 1150%higher than those of GC alloy,and 5.4%,3.8%and 15.4%higher than those of SC alloy.The UT+SC process significantly enhances the properties of cast Al-Li alloy.The increase of strength and elongation of Al-Li alloy prepared by UT+SC is at-tributed to the decrease of porosity,grain refinement and uniform distribution of the second phase.The combination of squeeze casting and ultrasonic treatment for the preparation of cast Al-Li alloys solves the poor alloy performance under gravity casting,and provides a new and effective method for the preparation of high strength and toughness cast Al-Li alloy to meet aerospace requirements.