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本文研究挤压铸造20／A356复合材料凝固组织与机械性能随凝固冷却速率的变化，并分析其断裂特征。实验结果表明：随着凝固冷却速率的降低，26／A356复合材料的X相晶粒度和共晶硅相尺寸均逐渐增大，其抗弯强度和弹性模量也随之降低。同时，由于优良的制造工艺，20／A356复合材料的抗弯强度和弹性模量分别达到521MPa和102GPa。处于国际先进水平。另外，挤压铸造A126／A356复合材料的凝固，起始于颗粒之间。颗粒表面是共晶硅相异质形核的基底。2／A356复合材料仍表现为脆断裂，断裂过程中：颗粒出现开裂和解理由阶，裂纹从脆性共晶硅相中开始生长，并逐渐向26颗粒扩展。
In this paper, the changes of solidification microstructure and mechanical properties of squeeze cast 20 / A356 composites with the cooling rate of solidification and the fracture characteristics are analyzed. The experimental results show that with the decrease of solidification cooling rate, both the X-phase grain size and eutectic silicon phase size of 26 / A356 composites increase gradually, and the flexural strength and elastic modulus decrease. At the same time, the flexural strength and elastic modulus of 20 / A356 composites reached 521MPa and 102GPa, respectively, due to the excellent manufacturing process. In the international advanced level. In addition, the solidification of Squeeze Cast A126 / A356 composites started between the particles. The surface of the particles is the base of the heterogeneous nuclei of the eutectic silicon phase. 2 / A356 composites still show brittle fracture. During the fracture process, the particles appear cracking and cleavage order, and the cracks begin to grow from the brittle eutectic silicon phase and gradually expand to 26 grains.