Wu Jian, Zhu Xinghua, Huang Sirui, Zhu Heguo
College of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, PR China.
Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, 610031, China.
Nanoscale. 2024 Aug 29;16(34):16260-16273. doi: 10.1039/d4nr02369b.
In this work, we successfully achieved an exceptional strength-ductility synergy in the brittle NiCoFe medium-entropy alloy (MEA) formation of a heterogeneous structure by doping with Si. The newly developed NiCoFeSi ( = 0.1, 0.2 and 0.3) MEAs exhibited a multi-phase heterogeneous structure consisting of face-centered cubic (FCC), body-centered cubic (BCC) and NiSi phases, with some B2 nanoparticles precipitated inside the BCC matrix. This multi-phase heterogeneous structure combined with precipitation hardening resulted in a dual enhancement in the strength and ductility of the alloys. Notably, the tensile strength and strain of the NiCoFeSi MEA were significantly increased to 1096.9 ± 39.0 MPa and 31.7 ± 0.3%, respectively, which were about 39.9% and 456.1% higher than those of the NiCoFe base alloy. Furthermore, density functional theory (DFT) results indicated that the charge redistribution caused by the addition of Si led to the presence of local charge enrichment and depletion regions, which facilitate plastic deformation and increase the ductility. The current study would provide valuable guidance to produce low-cost yet high-performance BCC-structured MEAs.
在这项工作中，我们通过掺杂Si成功地在脆性NiCoFe中熵合金（MEA）中实现了优异的强度-延展性协同效应，形成了异质结构。新开发的NiCoFeSi（= 0.1、0.2和0.3）中熵合金呈现出由面心立方（FCC）、体心立方（BCC）和NiSi相组成的多相异质结构，在BCC基体内部析出了一些B2纳米颗粒。这种多相异质结构与沉淀硬化相结合，导致合金的强度和延展性双重提高。值得注意的是，NiCoFeSi中熵合金的抗拉强度和应变分别显著提高到1096.9±39.0 MPa和31.7±0.3%，分别比NiCoFe基合金高约39.9%和456.1%。此外，密度泛函理论（DFT）结果表明，Si的添加引起的电荷重新分布导致了局部电荷富集和耗尽区域的存在，这有利于塑性变形并提高了延展性。当前的研究将为生产低成本但高性能的BCC结构中熵合金提供有价值的指导。
