低温下ZL101合金的裂纹扩展行为  

Crack Extension in ZL101 Alloy at Low Temperature

作　　者：马广辉[1] 李润霞[1] 白彦华[1] 李荣德[1] 

机构地区：[1]沈阳工业大学材料科学与工程学院,辽宁沈阳110870

出　　处：《铸造》2015年第10期960-963,共4页Foundry

基　　金：辽宁省创新团队项目(LT2002004)

摘　　要：对ZL101合金在20^-60℃拉伸过程中裂纹扩展行为进行研究,利用扫描电子显微镜观察断口形貌,并采用光学显微镜对断口附近组织和裂纹萌生和扩展形貌进行分析,研究裂纹扩展过程中铝基体内部应力的变化。结果表明:当温度由20℃下降至-60℃时ZL101合金的抗拉强度和屈服强度均有提高,而伸长率略有降低。ZL101合金在塑性变形过程中产生大量位错在Si相处塞积产生应力,使Si相发生解理断裂形成微裂纹,并且Si相断裂形成的解理面与附近的位错滑移带成135°角。在裂纹扩展过程中Si相的破裂使铝基体产生应力集中,在低温情况下Si相断裂所需的外加应力升高使断裂Si相之间铝基体的应力集中升高引发准解理断裂,导致合金伸长率下降。It was researched that the crack propagation behavior of ZL101 alloy between 20 ℃ and- 60 ℃ in the process of tension by this paper, the fracture morphology was observed using scanning electron microscope（SEM）, the microstructure near fracture and crack initiation and propagation morphology were analyzed by optical microscope, the inner stress changes in aluminum substrate were researched in the process of crack propagation. The experiment results show that the tensile strength and yield strength of ZL101 alloy were both improved when the temperature dropped from 20 ℃ to-60 ℃, but the elongation slightly decreased. A large number of dislocations were produced in the process of ZL101 alloy plastic deformation, they get along in the silicon phase to produce stress, which results that Si phase cleavage fracture to form micro cracks, and the cleavage plane and near dislocation slip band is 135 ° angle. Rupture of Si phase make aluminum substrate produce stress concentration in the process of crack propagation. It causes quasi-cleavage fracture that the applied stress increases of Si phase breaking under the condition of low temperature which makes the stress concentration of Al substrate between the fracture silicon phase increased, so the alloy elongation decreased.

关 键 词：铝硅合金 裂纹扩展 位错 硅相 低温 

分 类 号：TG146.21[一般工业技术—材料科学与工程]