TiAl_3对TiC粒子在铝基体中分布及α(Al)晶粒形核的影响

摘要

研究TiC和TiAl_3细化工业纯铝时TiAl_3的存在对TiC在铝基体中分布及α(Al)晶粒形核的影响,分析Al-Ti-C晶粒细化机制.结果表明:TiC单独作为工业纯铝的晶粒细化剂时,大量TiC被α(Al)晶粒推向树枝晶的晶界处,从而限制了TiC的异质形核作用;当TiC和TiAl_3共同作为晶粒细化剂时,在α(Al)晶粒内部出现了大量TiC粒子,大量的TiC粒子成为了α(Al)的结晶核心,并且在TiC颗粒和铝基体的界面处存在"富Ti过渡区";TiAl_3在铝熔体中分解释放出Ti原子并向TiC粒子周围偏聚,形成的"TiC/铝熔体界面富Ti过渡区" 改善了TiC与α(Al)的结构适应性,降低了TiC粒子的表面张力,促进了TiC粒子在铝熔体中的均匀分布,提高了其形核能力.%The effect of TiAl_3 on the distribution of TiC particles in aluminum matrix and nucleation of α(Al) grain was studied when the TiC and TiAl_3 refining industry aluminum, and the nucleation mechanism of Al-Ti-C grain refiner were discussed. The results show that when TiC alone is used as the nucleation phase, most of the TiC is pushed into the grain boundaries by the α(Al) dendrites and the nucleation of TiC is restricted. On the other hand, when TiC and TiAl_3 refine the industry aluminum together, most of the TiC particles are found within the α(Al) grains and nucleation occurs on TiC particles, and there is a Ti transition zone between TiC and aluminum interface. TiAl_3 releases Ti atoms in aluminum melt, Ti atoms congregate to the TiC surface, and ultimately forming TiC/aluminum interface Ti transition zone, which not only improves the structure of adaptability and wettability between TiC and Al , but also reduces the surface tension of TiC particles, which making a lot of TiC particles can be uniformly distributed in the aluminum melt, which advance α(Al) core and heterogeneous nucleation in the aluminum melt solidification.