Efficacy of borides in grain refining Al-Si alloys dataset

The grain refining efficacy of titanium, aluminium and niobium borides, as well as niobium aluminides, introduced via commercial and lab made master alloys on Al-Si alloys was investigated. Significant grain refinement is achieved via the introduction of these heterogeneous nuclei regardless of their nature, stoichiometry of the master alloy, and addition rate. However, the grain refinement is affected by variable such as contact time and cooling rate. In the case of borides, the chemical inoculation efficiency is greatly affected by their thermodynamic stability in molten Al-Si alloys. Conversely, the grain refining potency of properitectic Al₃Nb remains unaffected. The underlying grain refining mechanism was finally investigated using current model based on the growth restriction factor <i>Q</i> to simultaneously consider the effect of nucleants potency and alloy chemistry. Among Ti-, Al- and Nb-based borides with similar particle size and distribution, the latter are the most efficient to grain refine Al-Si alloys.

本研究针对通过商用及实验室制备的中间合金（master alloy）引入的硼化钛（titanium borides）、硼化铝（aluminium borides）、硼化铌（niobium borides）以及铝化铌（niobium aluminides），对铝硅（Al-Si）合金的晶粒细化效能展开了系统性研究。引入此类异质形核核心（heterogeneous nuclei）后，无论其种类、所用中间合金的化学计量比以及添加速率如何，均可实现显著的晶粒细化效果；然而，晶粒细化效果会受到接触时间与冷却速率等变量的影响。针对硼化物而言，其在铝硅合金熔体中的热力学稳定性会对化学孕育效率产生显著影响，与之相反，先共晶Al₃Nb（properitectic Al₃Nb）的晶粒细化效能则不受上述因素干扰。本研究最终采用基于生长限制因子Q（growth restriction factor Q）的现有模型，同时考量形核剂效能与合金成分的影响，对潜在的晶粒细化机制展开了深入分析；在粒径与分布相近的钛基、铝基及铌基硼化物中，铌基硼化物对铝硅合金的晶粒细化效果最为优异。