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采用K2ZrF4和KBF4混合粉末与铝熔体直接反应制备镁合金晶粒细化剂Al-5Zr-1B合金,利用光学显微镜、X射线衍射仪和扫描电镜,研究了Al-5Zr-1B合金的显微组织及其对纯Mg和AZ31镁合金的晶粒细化作用。结果表明:Al-5Zr-1B合金中含有大量细小的ZrB2粒子,平均尺寸为0.2μm,ZrB2粒子作为异质形核核心使纯Mg和AZ31镁合金晶粒得到细化。随着Al-5Zr-1B合金添加量的增加,纯Mg和AZ31镁合金的晶粒尺寸逐渐减小。添加0.3%(质量分数)的Al-5Zr-1B合金,可使纯Mg晶粒从1400μm细化到120μm。添加0.6%的Al-5Zr-1B合金,可使AZ31镁合金晶粒从170μm细化到45μm。
The Al-5Zr-1B magnesium alloy grain refiner Al-5Zr-1B alloy was prepared by direct reaction of K2ZrF4 and KBF4 powders with aluminum melt. The microstructure of Al-5Zr-1B alloy was studied by optical microscope, X-ray diffraction and scanning electron microscope Tissue and its grain refinement of pure Mg and AZ31 magnesium alloy. The results show that a large amount of fine ZrB2 particles are contained in Al-5Zr-1B alloy with an average size of 0.2μm. ZrB2 particles as heterogeneous nuclei are refined into pure Mg and AZ31 magnesium alloy grains. With the addition of Al-5Zr-1B alloy, the grain size of pure Mg and AZ31 magnesium alloy decreases gradually. Add 0.3% (mass fraction) of Al-5Zr-1B alloy, pure Mg grains can be refined from 1400μm to 120μm. Adding 0.6% Al-5Zr-1B alloy, AZ31 magnesium alloy grains can be refined from 170μm to 45μm.