挤压变形对SiC_w/ZK51A镁基复合材料组织和性能的影响

Extrusion deformation on microstructure and mechanical properties of SiC_w/ZK51A magnesium matrix composite

利用透射电镜、扫描电镜和拉伸试验等实验方法 ,研究了铸态和挤压态SiCw/ZK51A镁基复合材料的组织与力学性能。结果表明 ,挤压铸造SiCw/ZK51A复合材料经等温热挤压后 ,其力学性能有很大提高。主要原因是 :挤压变形能消除铸造缺陷 ,增强SiC晶须与ZK51A镁合金基体的界面结合 ,使复合材料中SiC晶须发生定向分布 ,沿挤压方向呈准一维分布特征 ,晶须的增强承载能力得到充分发挥。

The microstructure, fracture morphology, and mechanical properties of both squeeze cast and subsequently isothermally extruded SiC w/ZK51A magnesium matrix composite were experimentally investigated by means of transmission electron microscopy, scanning electron microscopy, and tension test respectively. The results show that the as extruded composite possesses much higher mechanical properties than the as cast composite, especially modulus of elasticity and mechanical strength. The main reason for this lies in that the extrusion deformation not only helps to improve the whisker/matrix interfacial bonding and to eliminate casting defects, but also makes the SiC whiskers tend to align uniformly and quasi unidirectionally in the extrusion direction, leading to excellent reinforcing effect by load transfer. [