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采用金相显微镜、扫描电子显微镜、透射电子显微镜和差示扫描量热法研究Al-0.66Mg-0.85Si合金在均匀化过程中的组织演变。合金铸态组织呈典型的枝晶形貌,存在α(Al)、Al15(FeMn)3Si2、Mg2Si,、Q(Al1.9CuMg4.1Si3.3)和Si相。铸态组织中存在2种不同晶体结构的Mg2Si相,一种是在铸造过程中形成的,另一种是在铸造完成后的空冷过程中形成的。经过545°C、20 h均匀化处理之后,组织中的Q、Mg2Si和Si相已完全溶入基体,残留的第二相主要是Al15(FeMn)3Si2相。Al15(FeMn)3Si2相的尺寸减小、球化并且在晶界上断续分布。在铸态和均匀化热处理状态中,均未发现含Zn相。
The microstructure evolution of Al-0.66Mg-0.85Si alloy during homogenization was investigated by metallographic microscope, scanning electron microscopy, transmission electron microscopy and differential scanning calorimetry. The as-cast microstructure of the alloy shows a typical dendritic morphology with α (Al), Al15 (FeMn) 3Si2, Mg2Si, Q (Al1.9CuMg4.1Si3.3) and Si phases. There are two kinds of Mg2Si phases with different crystal structures in the as-cast microstructure, one formed during the casting process and the other formed during the air-cooling process after the casting process. After homogenization at 545 ° C for 20 h, the Q, Mg2Si and Si phases in the microstructure completely dissolved into the matrix, and the second phase remained mainly Al15 (FeMn) 3Si2 phase. The Al15 (FeMn) 3Si2 phase is reduced in size, spheroidized and discontinuous in grain boundaries. In the as-cast and homogenized heat-treated state, no Zn-containing phase was found.