熔体冷却速率和热处理对A359铝合金力学性能的影响

Effects of Melt Cooling Rate and Heat Treatment on Mechanical Properties of A359 Aluminum Alloy

采用阶梯金属型制备了在不同熔体冷却速率下的A359铝合金试样,并对其进行了T6热处理。研究了冷却速率及热处理对合金力学性能的影响。结果表明,随冷却速率提高,铸态和T6态A359铝合金的抗拉强度及伸长率同时提高。结合合金微观组织表征及金属强韧化理论,分析了冷却速率对合金力学性能演变的影响。分析表明,随冷却速率提高,非平衡凝固组织中微观组织的细化、溶质原子的过饱和固溶、Al基体中出现的大量纳米Si颗粒和共晶Si中出现的大量纳米Al颗粒共同导致了A359铝合金强度、塑性的同时提高。

The A359 alloy was prepared by lattice-type metal mold with different melt cooling rates,and further treated by T6heat treatment.On this basis,the effects of melt cooling rate and heat treatment on the mechanical properties of the alloy were investigated.The results indicate that the tensile strength and elongation of the ascast and T6treated alloys are increased simultaneously with the increase of melt cooling rate.Furthermore,the influence mechanism of melt cooling rate on the evolution of mechanical properties of the alloy was analyzed combining with the microstructure characterization and the theory of metal strengthening and toughening.The strength and ductility of the A359 alloy are increased simultaneously with the increase of melt cooling rate,which is mainly attributed to the refinement of non-equilibrium solidification microstructure,supersaturated solution of solute atoms,large amounts of nano Si particles in Al matrix and large amounts of nano Al particles in eutectic Si.