Abstract The grain refining behaviour of a novel Al-Ti-Nb-B alloy in Al-Si melt with low cooling rate was in-situ observed by synchrotron radiography. Nucleation and growth of α-Al dendrites in the near-isothermal Al-8Si-7Cu melts inoculated by Al-1.67Ti-3.33Nb-0.5B and Al-5Ti-1B and were investigated. The evolution of grain number density and dendrite growth rate of α-Al were quantitatively studied, with which the significant difference in nucleation potencies between TiB2 and (Ti,Nb)B2 in Al-Si melt was understood. The superior grain refining efficacy of the Al-1.67Ti-3.33Nb-0.5B alloy owes to the sufficient amount of (Ti,Nb)B2 particles potent for both epitaxial nucleation and free growth.

中文翻译：

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Al-Ti-Nb-B合金接种亚共晶Al-Si合金晶粒细化动力学的原位观察

摘要 用同步辐射照相原位观察了一种新型Al-Ti-Nb-B合金在低冷却速度Al-Si熔体中的晶粒细化行为。研究了 Al-1.67Ti-3.33Nb-0.5B 和 Al-5Ti-1B 孕育的近等温 Al-8Si-7Cu 熔体中 α-Al 枝晶的形核和生长。定量研究了α-Al 晶粒数密度和枝晶生长速率的演变，从而理解了Al-Si 熔体中TiB2 和(Ti,Nb)B2 成核能力的显着差异。Al-1.67Ti-3.33Nb-0.5B 合金优异的晶粒细化功效归功于足够数量的 (Ti,Nb)B2 颗粒，它们对外延成核和自由生长都有效。