材料期刊网

研究不同镁含量对触变成形A319合金显微组织和拉伸性能的影响。合金在含50%液相时进行触变成形，并对部分合金进行T6热处理。采用光学显微镜、扫描电子显微镜、能量散射谱、X射线衍射和拉伸试验对合金进行表征。结果表明，镁可以细化合金中共晶硅。当镁含量为1.0%和1.5%时，合金中形成致密的Al9FeMg3Si5相。随着镁含量的增加，触变成形合金的拉伸强度增加。热处理后的触变成形A319合金的抗拉强度、屈服强度和伸长率分别为298 MPa，201 MPa和4.5%。而对于添加1.5%Mg的触变成形A319合金，其热处理后的抗拉强度、屈服强度和伸长率分别为325 Pa、251 MPa和1.4%。触变成形A319合金表现为韧窝断裂，而添加1.5%Mg的A319合金表现为混合断裂，在合金表面可观察到韧窝断裂和解理断裂。

The effects of Mg content on the microstructure and tensile properties of thixoformed A319 alloys were studied. The samples were thixoformed at 50%liquid content and some of the thixoformed samples were subjected to the T6 heat treatment. The samples were then examined by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy and X-ray diffraction (XRD) analysis as well as tensile tests. The results showed that magnesium was able to refine the eutectic silicon in the samples. It was also observed that a compact Al9FeMg3Si5 phase was formed when the magnesium content was 1.0% and 1.5%. The results also revealed that as the magnesium content in the alloy increases, the tensile strengths of the thixoformed alloys also increase. The ultimate tensile strength, yield strength and elongation to fracture of the thixoformed A319 heat treated alloy were 298 MPa, 201 MPa and 4.5%, respectively, whereas the values of the thixoformed heat treated alloy with 1.5%Mg content were 325 MPa, 251 MPa and 1.4%, respectively. Thixoformed A319 alloy showed a dimple fracture behaviour, while thixoformed A319 alloys with 1.5%Mg showed a mixed mode fracture behaviour, where dimple and cleavage ruptures were seen on the fracture surface of the samples.