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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Al9Fe Mg3Si5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 different magnesium contents on the microstructure and tensile properties of thixoformed A319 alloy were studied. The alloy is thixo-formed at 50% liquid phase and T6 heat-treated to some alloys. The alloys were characterized by optical microscope, scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction and tensile test. The results show that magnesium can be refined alloy eutectic silicon. When the content of magnesium is 1.0% and 1.5%, a dense Al9Fe Mg3Si5 phase is formed in the alloy. As the magnesium content increases, the tensile strength of thixoformed alloys increases. The tensile strength, yield strength and elongation of the thixoformed A319 alloy after heat treatment were 298 MPa, 201 MPa and 4.5%, respectively. And for the thixoformed A319 alloy with 1.5% Mg addition, the tensile strength, yield strength and elongation after heat treatment are 325 Pa, 251 MPa and 1.4% respectively. The thixoformed A319 alloy showed ductile fracture, while the A319 alloy with 1.5% Mg showed mixed fracture, dimple fracture and cleavage fracture were observed on the alloy surface.