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采用原位反应近液相线铸造方法制备含有3.6%(质量分数)原位Al2O3颗粒的Al-6.8Cu基复合材料,在基体合金的固液两相区选择580,590,600℃和610℃进行二次加热保温实验,淬火固定其半固态组织。通过光学显微镜及透射电镜观察合金的组织结构,研究Al2O3原位颗粒对材料组织的影响。结果表明:原位Al2O3颗粒对Al-6.8Cu合金的铸态组织具有一定的细化作用,但没有明显的球化作用。在半固态二次加热过程中原位Al2O3颗粒对晶粒长大行为具有抑制作用和球化作用,与基体合金相比,在相同的二次加热条件下晶粒尺寸减小20~40μm。
Al-6.8Cu-based composites containing 3.6% (mass fraction) Al 2 O 3 particles were prepared by in-situ reactive near-liquid-phase casting. The solid-liquid two-phase region of the matrix alloy was heated at 580,590,600 ℃ and 610 ℃ for secondary heating Insulation experiments, quenching its semi-solid tissue. The microstructure of the alloy was observed by optical microscope and transmission electron microscope, and the effect of Al2O3 in-situ particles on the microstructure of the alloy was investigated. The results show that the Al2O3 particles in situ have a refining effect on the as-cast microstructure of Al-6.8Cu alloy, but no obvious spheroidization. The in-situ Al2O3 particles inhibited the growth of grains and spheroidized during the semi-solid secondary heating. Compared with the matrix alloy, the grain size decreased by 20-40 μm under the same secondary heating conditions.