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在2219铝合金凝固阶段添加不同质量分数的Al-Ti-C细化剂,利用光学显微镜(OM)、差示量热法(DSC)等研究了铸锭的凝固组织,并从合金的微观组织及过冷度演变规律展开研究,探讨Al-Ti-C细化剂对2219合金铸锭组织的细化机理。结果表明,Al-Ti-C细化剂的添加能促使晶粒细化,且细化剂含量为0.5%时具有最佳的细化效果;铝熔体过冷度随着晶粒细化剂含量的增加而呈递减趋势,当Al-Ti-C含量大于0.5%时,过冷度不再显著降低;Al-Ti-C熔化后分解出的TiC粒子可作为异质形核核心,凝固阶段TiC粒子的团聚导致形核基底颗粒增大,使得润湿角与临界形核能下降,减小了熔体形核时所需过冷度。
Al-Ti-C refiner with different mass fraction was added into the 2219 aluminum alloy during solidification stage. The microstructure of the ingot was studied by optical microscope (OM) and differential scanning calorimetry (DSC) And the evolution of undercooling, the mechanism of refinement of 2219 alloy ingot by Al-Ti-C refiner was discussed. The results show that the addition of Al-Ti-C refiner can promote the grain refinement, and the refiner has the best refining effect when the refiner content is 0.5%. The degree of undercooling of aluminum melt decreases with the grain refiner The content of Al-Ti-C decreases with the increasing of Al-Ti-C content. When the content of Al-Ti-C is more than 0.5%, the supercooling degree does not decrease significantly. TiC particles decomposed after Al-Ti-C melt can be used as heterogeneous nucleation centers, The agglomeration of TiC particles leads to the increase of nucleation base particles, which leads to the decrease of wetting angle and critical nucleation energy, and reduces the degree of subcooling required for melt nucleation.