Abstract 1.2 Hf and 1.5 Y2O3 (wt.%) were added into CoCrFeNi (CCFN) high-entropy alloy (HEA) to fabricate oxide dispersion strengthened CoCrFeNi (ODS-CCFN) composite by mechanical alloying and spark plasma sintering. Microstructures, including XRD, SEM, EBSD, and TEM of CCFN and ODS-CCFN HEAs were investigated to identify the effects of introducing nano-sized oxides into CCFN HEA. These HEAs compose of FCC matrix and a small amount of Cr7C3 and Cr2O3, and a few of MnCr2O4 is only detected in CCFN HEA. High-density Y2Hf2O7 with the average diameter of 6.9 ± 4.2 nm uniformly distribute in the matrix and Cr7C3 of ODS-CCFN. Lattice misfit calculations indicate that Y2Hf2O7 particles exhibit a coherent interface with the matrix, and a semi-coherent interface with Cr7C3. The average sizes of all phases, including grain, Cr7C3 and Cr2O3, are highly refined in ODS-CCFN. The effects of microstructure changes on properties of CCFN HEA were also detected. Compared with CCFN, the tensile yield strength of ODS-CCFN increases from 978 MPa to 1.25 GPa with a reasonable elongation decreases from 2.6% to 1.9%. The increase in yield strength for ODS-CCFN is mainly ascribed to the precipitation strengthening of Y2Hf2O7 and highly refined grains, Cr7C3 and Cr2O3. The electrical resistivity of ODS-CCFN is lower than that of CCFN, the reason may be that the existence of Y2Hf2O7 particles reduce the lattice distortion of the matrix, and make the electrical resistivity decrease. The corrosion resistance of ODS-CCFN HEA is highly improved in both sulfuric acid solution and sodium chloride solution because its passive current density is largely reduced by the addition of Hf and Y2O3.

中文翻译：

---

机械合金化和放电等离子烧结氧化物弥散强化CoCrFeNi高熵合金的组织和力学性能

摘要 在CoCrFeNi（CCFN）高熵合金（HEA）中加入1.2 Hf和1.5 Y2O3（wt.%），通过机械合金化和放电等离子烧结制备氧化物弥散强化CoCrFeNi（ODS-CCFN）复合材料。研究了 CCFN 和 ODS-CCFN HEA 的微观结构，包括 XRD、SEM、EBSD 和 TEM，以确定将纳米级氧化物引入 CCFN HEA 的效果。这些 HEA 由 FCC 基体和少量 Cr7C3 和 Cr2O3 组成，少数 MnCr2O4 仅在 CCFN HEA 中检测到。平均直径为 6.9 ± 4.2 nm 的高密度 Y2Hf2O7 均匀分布在 ODS-CCFN 的基体和 Cr7C3 中。晶格失配计算表明 Y2Hf2O7 颗粒与基体呈现相干界面，与 Cr7C3 呈现半相干界面。所有相的平均尺寸，包括晶粒、Cr7C3 和 Cr2O3，在 ODS-CCFN 中高度精炼。还检测了微观结构变化对 CCFN HEA 性能的影响。与CCFN相比，ODS-CCFN的拉伸屈服强度从978 MPa提高到1.25 GPa，延伸率从2.6%降低到1.9%。ODS-CCFN 屈服强度的提高主要归因于 Y2Hf2O7 和高度细化晶粒 Cr7C3 和 Cr2O3 的析出强化。ODS-CCFN的电阻率低于CCFN，原因可能是Y2Hf2O7粒子的存在降低了基体的晶格畸变，使电阻率降低。ODS-CCFN HEA 在硫酸溶液和氯化钠溶液中的耐腐蚀性能都有很大提高，因为 Hf 和 Y2O3 的加入大大降低了其钝化电流密度。还检测了微观结构变化对 CCFN HEA 性能的影响。与CCFN相比，ODS-CCFN的拉伸屈服强度从978 MPa提高到1.25 GPa，延伸率从2.6%降低到1.9%。ODS-CCFN 屈服强度的提高主要归因于 Y2Hf2O7 和高度细化晶粒 Cr7C3 和 Cr2O3 的析出强化。ODS-CCFN的电阻率低于CCFN，原因可能是Y2Hf2O7粒子的存在降低了基体的晶格畸变，使电阻率降低。ODS-CCFN HEA 在硫酸溶液和氯化钠溶液中的耐腐蚀性能都有很大提高，因为 Hf 和 Y2O3 的加入大大降低了其钝化电流密度。还检测了微观结构变化对 CCFN HEA 性能的影响。与CCFN相比，ODS-CCFN的拉伸屈服强度从978 MPa提高到1.25 GPa，延伸率从2.6%降低到1.9%。ODS-CCFN 屈服强度的提高主要归因于 Y2Hf2O7 和高度细化晶粒 Cr7C3 和 Cr2O3 的析出强化。ODS-CCFN的电阻率低于CCFN，原因可能是Y2Hf2O7粒子的存在降低了基体的晶格畸变，使电阻率降低。ODS-CCFN HEA 在硫酸溶液和氯化钠溶液中的耐腐蚀性能都有很大提高，因为 Hf 和 Y2O3 的加入大大降低了其钝化电流密度。