A1-Si过共晶合金拉伸断裂过程的研究

Research of Tension Fracture Process of Al-Si Hypereutectic Alloy

以铸造Al-Si过共晶合金为研究对象,采用现场金相显微镜对Al-Si过共晶合金的断裂过程进行观察,探讨了两相合金的断裂机理。试验发现:Al-Si过共晶合金的断裂首先发生在先析Si相的凹角处,随着外力的增加,裂纹向先析Si相内部进行扩展,达到相界处时改变方向,沿着Al-Si两相的相界进行扩展。分析认为:Al-Si两相合金中,相界的结合强度最弱,裂纹的扩展是择弱进行的。

Fracture mechanism of two-phase alloy is discussed based on the observation of the fracture process of Al-Si hypereutectic alloy by Using optical microscopy. It is found that the fracture of Al-Si hypereutectic alloy occurs firstl on the nook of primary silicon and with the increase of outer forces, the crack expands to the internal of primary silicon and the direction changes at the phase boundary and expands along the phase boundary. Analysis suggests that the bonding strength Of the phase boundary is the weakest and crack propagation occurs preferably in the weak for Al-Si two-phase alloy.