挤压铸造对过共晶Al-Si-Cu-Mg合金组织与性能的影响

Effect of Squeeze Casting on Microstructures and Mechanical Properties of Hypereutectic Al-Si-Cu-Mg Alloy

研究了比压对挤压铸造Al-17.5Si-4Cu-0.5Mg-0.1Mn合金的显微组织和力学性能的影响规律。结果表明,在压力下凝固时,合金的显微组织发生明显改善,力学性能大幅提高。且在一定压力范围内,随着挤压力的增加,α(Al)枝晶明显细化,枝晶间距减小,共晶Si相、Al2Cu相等强化相尺寸减小,力学性能提高;但当挤压铸造比压达到850 MPa时,合金的硬度和强度反而略有下降。与此同时,合金的伸长率却随着挤压铸造比压的增大持续升高。因此,比压为670 MPa时,挤压铸造Al-17.5Si-4Cu-0.5Mg-0.1Mn合金获得较好的组织与性能。

Microstructure and mechanical properties of Al-17.5Si-4Cu-0.5Mg-0.1Mn alloy with different applied solidification pressures have been investigated. With the pressures applied during solidification, the microstructure of the alloy showed significant change, and the mechanical properties of the alloy were improved remarkably. As the squeeze pressure increased in a certain range, the α （A1） dendrites was obviously refined and the dendrite arm spacing was decreased, the size ofeutectic Si and A12Cu phases reduced significantly. When the squeeze pressure reaches 850 MPa, the microstructure of alloy was coarsened, the mechanical properties of the alloy showed little reduction, with the increasing of casting specific pressure the elongation of alloy was increased. The proper specific pressure is 676 MPa for Al-17.5 Si-4Cu-0.5Mg-0.1Mn alloy.