Grain refinement of a NiCoFe medium entropy alloy: composition design from solute interaction perspective
Grain refinement of a NiCoFe medium entropy alloy: composition design from solute interaction perspective
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DOI：
10.1016/j.jallcom.2023.169966
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发表时间：
2023-04
影响因子：
6.2
通讯作者：
Z. Yin;X. Liu;N. Gao;S.R. Li;J. Yao;Z. Fan;W.B. Zhang;Y.Z. Wang
中科院分区：
文献类型：
--
作者：
Z. Yin;X. Liu;N. Gao;S.R. Li;J. Yao;Z. Fan;W.B. Zhang;Y.Z. Wang
混合熵在1 R和1.5 R之间的中熵合金（MEA），例如，NiCoFe合金在77K下具有优异的比强度和断裂韧性等性能。然而，它们的粗柱状组织导致较差的机械性能。在这里，溶质对凝固组织的影响进行了研究，目的是细化晶粒。首先，单独添加C导致柱状等轴转变（CET），并使（NiCoFe）97C3MEA的平均晶粒尺寸达到210 µm。此外，基于溶质相互作用的考虑，将Cr添加到C掺杂MEA中。在凝固过程中，C和Cr在固液界面之前的相互作用导致（NiCoFeCr0.25）97C3MEA的晶粒尺寸进一步减小至164 µm。CET和晶粒细化归因于凝固界面前的附加成分过冷。晶粒细化导致屈服强度、极限抗拉强度、加工硬化率的显著提高，而延伸率略有牺牲。
The medium entropy alloys (MEAs) with mixing entropy between 1 R and 1.5 R e.g., NiCoFe alloy, exhibit unique properties, such as excellent specific strength and fracture toughness at 77 K. However, their coarse columnar microstructures lead to poor mechanical properties. Here, the solute effects on as-solidified structures were studied with the aim of grain refinement. First, sole addition of C leads to columnar to equiaxed transition (CET) and achieves an average grain size of 210 µm for (NiCoFe)97C3MEA. Further, based on the consideration of solute interaction, Cr was added into the C-doping MEA. The interaction of C and Cr ahead of the solid-liquid interface during solidification results in further grain size reduction to 164 µm for the (NiCoFeCr0.25)97C3MEA. The CET and grain refinement are attributed to the additional constitutional supercooling ahead of solidification interface. The grain refinement leads to significant improvement of yield strength, ultimate tensile strength, work hardening rate and slight sacrifice of elongation.