Rapid dendrite growth in single- or dual-phase multicomponent alloys can be manipulated to improve the mechanical properties of such metallic materials. Rapid growth of (αFe) dendrites was realized in an undercooled Fe-5Ni-5Mo-5Ge-5Co (wt.%) multinary alloy using the glass fluxing method. The relationship between rapid dendrite growth and the micro-/nano-mechanical properties of the alloy was investigated by analyzing the grain refinement and microstructural evolution resulting from the rapid dendrite growth. It was found that (αFe) dendrites grow sluggishly within a low but wide undercooling range. Once the undercooling exceeds 250 K, the dendritic growth velocity increases steeply until reaching a plateau of 31.8 ms[superscript −1]. The increase in the alloy Vickers microhardness with increasing dendritic growth velocity results from the hardening effects of increased grain/phase boundaries due to the grain refinement, the more homogeneous distribution of the second phase along the boundaries, and the more uniform distribution of solutes with increased contents inside the grain, as verified also by nanohardness maps. Once the dendritic growth velocity exceeds ~8 ms[superscript −1], the rate of Vickers microhardness increase slows down significantly with a further increase in dendritic growth velocity, owing to the microstructural transition of the (αFe) phase from a trunk-dendrite to an equiaxed-grain microstructure.
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机译:可以控制单相或双相多组分合金中树枝状晶体的快速生长,以改善此类金属材料的机械性能。使用玻璃熔剂法在过冷的Fe-5Ni-5Mo-5Ge-5Co(wt。%)多元合金中实现了(αFe)树突的快速生长。通过分析由快速枝晶生长引起的晶粒细化和微观结构演变,研究了快速枝晶生长与合金的微观/纳米机械性能之间的关系。发现在低但过宽的过冷范围内,(αFe)树枝状晶体生长缓慢。一旦过冷度超过250 K,树枝状生长速度就急剧增加,直到达到31.8 ms [上标-1]的平稳期。合金维氏显微硬度随树枝状晶体生长速度的增加而增加,这是由于晶粒细化导致晶粒/相边界增加而产生的硬化作用,沿边界的第二相分布越均匀以及溶质分布越均匀而导致的。纳米硬度图也证实了晶粒内部的含量。一旦树枝状晶体的生长速度超过〜8 [ms [上标-1],维氏显微硬度的增加速度就会显着降低,这是由于(αFe)相从主干-树枝状晶体向微观结构转变的结果。等轴晶组织。
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