The damage evolution under thermal fatigue loading for AlSi10Mg (Cu) cast alloy on the crack initiation and early propagation stage, mainly focusing on the influence of silicon particles on the thermal fatigue crack behaviour. The results show that, thermal fatigue crack origins from the failure interfaces between debonded silicon particles and matrix, that is because of the difference in thermal expansion coefficient between silicon particles and aluminum matrix, thus leading to the misfit of thermal strain, finally caused cyclic stress on the interfaces with fatigue failure. The propagation of thermal fatigue crack related to the growth on both length and width direction, ductile dendrite hinders the propagation of fatigue crack. The result of simulation analysis about the stress distribution around silicon particles during thermal fatigue is given to help discuss the experiment results.%微观观察AlSi10Mg (Cu) 铸铝合金在热疲劳裂纹的萌生和早期扩展过程, 重点研究共晶硅粒子对热疲劳裂纹行为的影响.结果表明:热疲劳裂纹萌生于脱粘共晶硅粒子与铝基体间的开裂界面, 原因是共晶硅粒子与铝基体的热膨胀系数不同, 引起热循环过程中两相热应变不协调, 从而在两相界面处产生循环应力而引起疲劳破坏.热疲劳裂纹的扩展在长度和宽度上同时进行, 具有良好塑性的铝枝晶对疲劳裂纹的扩展起阻碍作用.对热疲劳过程中共晶硅粒子周围应力场的模拟分析进一步解释了实验现象.
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