The effects of high undercooling and a large cooling rate can be achieved by the use of a containerless drop tube technique, which is conducive to rapid solidification and formation of a metastable phase. Here, the rapid solidification of Fe 78 Si 13 B 9 (S 1 ) and Fe 78 Si 9 B 13 (S 2 ) alloys was completed under microgravity condition. Based on theoretical calculations, a maximum undercooling of 433 K (0.29 T L ) and 412 K (0.28 T L ) was obtained, respectively. The microstructure evolution and the formation of an amorphous-nanocrystalline structure for the two alloys were compared and analyzed. The results show that S 2 alloy has better amorphous forming ability and higher hardness. During the solidification of S 1 alloy, the primary phase α-Fe grows by the manner of dendrites, and the secondary dendrite arm spacing decreases exponentially with increased undercooling. An amorphous-nanocrystalline structure is developed when the undercooling is increased up to 388 K; S 2 alloy forms an amorphous-nanocrystalline structure at an undercooling of 275 K and is completely amorphized after exceeding an undercooling of 402 K. In addition, the hardness and elastic modulus are acquired by nanoindentation technology under different degrees of undercooling. The phase constitution, morphology, distribution, and grain refinement of the alloys have important effects on the micromechanical properties of these alloys.

中文翻译：

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Fe-B-Si合金快速凝固过程中晶体向金属玻璃的转变及微观力学性能变化

采用无容器滴管技术可以达到高过冷度和大冷却速度的效果，有利于快速凝固并形成亚稳相。在此，Fe 78 Si 13 B 9 (S 1 )和Fe 78 Si 9 B 13 (S 2 )合金的快速凝固在微重力条件下完成。根据理论计算，分别获得了 433 K (0.29 TL ) 和 412 K (0.28 TL ) 的最大过冷度。对两种合金的微观结构演变和非晶-纳米晶结构的形成进行了比较和分析。结果表明，S 2 合金具有更好的非晶形成能力和更高的硬度。S 1 合金在凝固过程中，初生相α-Fe以枝晶的方式生长，二次枝晶臂间距随着过冷度的增加呈指数减小。当过冷度增加到 388 K 时，形成非晶-纳米晶结构；S 2 合金在275 K过冷度下形成非晶-纳米晶结构，超过402 K过冷度后完全非晶化。此外，在不同过冷度下通过纳米压痕技术获得硬度和弹性模量。合金的相组成、形貌、分布和晶粒细化对这些合金的微观力学性能有重要影响。S 2 合金在275 K过冷度下形成非晶-纳米晶结构，超过402 K过冷度后完全非晶化。此外，在不同过冷度下通过纳米压痕技术获得硬度和弹性模量。合金的相组成、形貌、分布和晶粒细化对这些合金的微观力学性能有重要影响。S 2 合金在275 K过冷度下形成非晶-纳米晶结构，超过402 K过冷度后完全非晶化。此外，在不同过冷度下通过纳米压痕技术获得硬度和弹性模量。合金的相组成、形貌、分布和晶粒细化对这些合金的微观力学性能有重要影响。