Zhang Jingyu, Xiong Ke, Huang Lin, Xie Bo, Ren Daping, Tang Chen, Feng Wei
School of Mechanical Engineering, Chengdu University, Chengdu 610106, China.
Sichuan Province Engineering Technology Research Center of Powder Metallurgy, Chengdu 610106, China.
Materials (Basel). 2023 Sep 26;16(19):6407. doi: 10.3390/ma16196407.
A series of five-element CoCrFeNi-Nbx (x = 0, 1, 3, 5, 7, and 9 wt%) high-entropy alloys were prepared using high-energy ball milling and discharge plasma sintering methods. Then, the effects of doping with Nb elements on the organization and properties of the CoCrFeNi HEAs were systematically investigated by tensile testing, hardness testing, and examining their micro-morphologies. The results show that with the addition of the Nb element, the lattice distortion of the alloy due to the large size of the Nb atoms causes the microstructure of CoCrFeNi HEAs to change from a single-phase FCC structure to a dual-phase structure of FCC and Laves. With the increase in the Nb content, the increase in the volume fraction of the hard and brittle Laves phase leads to the enhancement of the HEA's tensile strength, yield strength, and hardness, and a decrease in plasticity. The Nb5 alloy showed the most excellent comprehensive performance, with a tensile strength, yield strength, and plasticity of 879.1 MPa, 491.8 MPa, and 39.8%, respectively, and all the properties were improved compared with those of the HEAs obtained by the arc melting method. The increase in the hardness of the HEAs was nearly proportional to the increase in the volume fraction of the Laves phase, which was the direct cause of the increase in the hardness of the HEA. Therefore, since the Laves phase is the direct cause of the increase in HEA hardness, the doping of CoCrFeNi HEAs with Nb can significantly improve the properties of HEAs.
采用高能球磨和放电等离子烧结方法制备了一系列五元素CoCrFeNi-Nbx（x = 0、1、3、5、7和9 wt%）高熵合金。然后，通过拉伸试验、硬度测试以及观察其微观形貌，系统研究了Nb元素掺杂对CoCrFeNi高熵合金组织和性能的影响。结果表明，随着Nb元素的加入，由于Nb原子尺寸较大导致合金晶格畸变，使得CoCrFeNi高熵合金的微观结构从单相FCC结构转变为FCC和Laves双相结构。随着Nb含量的增加，硬脆Laves相体积分数的增加导致高熵合金的抗拉强度、屈服强度和硬度提高，而塑性降低。Nb5合金表现出最优异的综合性能，其抗拉强度、屈服强度和塑性分别为879.1 MPa、491.8 MPa和39.8%，与电弧熔炼法制备的高熵合金相比，各项性能均有所提高。高熵合金硬度的增加几乎与Laves相体积分数的增加成正比，这是高熵合金硬度增加的直接原因。因此，由于Laves相是高熵合金硬度增加的直接原因，Nb掺杂CoCrFeNi高熵合金可显著改善高熵合金的性能。
