深过冷Fe-B-Si共晶合金凝固组织纳米化机制探讨

采用深过冷及深过冷加水淬的方法，成功地制备了样品直径为16mm，高为15mm，组织中晶粒平均尺寸小于120nm的Fe76B12Si12合金块体纳米材料。理论分析与实际计算结果表明：该合金凝固组织纳米化的主要原因在于，其共晶两相的生长速度小、组织粗化速率小、溶质平衡分配系数低以及具有相对较低的熔化焓；深过冷Fe-B-Si合金块体纳米软磁材料制备的理想条件是：获得超过冷、选择主要由溶质扩散控制生长的共晶合金成分、获得Fe2B(Si)相为完全准球状形态的二次粒化非规则共晶组织。

Nanocrystallization mechanism of solidified microstructure of highly undercooled eutectic Fe -B -Si alloy

A bulk Fe 76 B 12 Si 12 nanocrystalline soft magnetic material,with a diameter 16 mm and a height 15 mm, with an average grain size less than 120 nm was prepared by highly undercooling and quenching the high undercooled alloy into water. On basis of theoretical analysis and calculation,it is proposed that this alloy has smaller eutectic phase growth and coarsening rate and has smaller solute equilibrium partition coefficient and melting entropy, compared with other alloys, and these are the main reasons for the nanocrystallization of the microstructure. Three ideal conditions for preparing bulk nanometeric Fe-B-Si eutectic soft magnetic material are: to achieve hypercooling state, to select the composition of eutectic alloy whose growth was mainly controlled by solute diffusion and to obtain second granular anomalous eutectic structure with quasi spheric morphology of Fe 2B(Si).