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Al 元素对 CoFeNi2(V2.5C)0.2 共晶高熵合金微观组织及力学性能的影响
Effect of Aluminium Addition on the Microstructureand Mechanical Properties of a CoFeNi2(V2.5C)0.2 Eutectic High-entropyAlloy
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- DOI:
- 作者:
- 谢衡科 1，2，任驰骋 2，闫朝宁 1，周小淞 1，颜非亚 1，李天昕 1，2
XIE Hengke1,2,REN Chicheng2,YAN Chaoning1,ZHOU Xiaosong1,YAN Feiya1,LI Tianxin1,2
- 作者单位:
- 1. 贵阳铝镁设计研究院有限公司，贵州 贵阳 550003；2. 贵州大学 材料与冶金学院，贵州 贵阳 550025
1. Guiyang Aluminum Magnesium Design & Research Institute Co., Ltd., Guiyang 550003,China; 2. School of Materials and Metallurgy, Guizhou University, Guiyang 550025,China
- 关键词:
- 共晶高熵合金；成分设计；微观组织；力学性能；固溶强化
eutectic high-entropy alloys; component design; microstructure; mechanical properties; solid solution strengthening
- 摘要:
- 共晶高熵合金因其优异的力学性能及出色的铸造流动性得到材料领域的广泛关注。其中，含 C 共晶高熵合金是近年发展起来的一种新型设计体系，虽展现出良好的塑性，但较低的屈服强度是制约其工程应用的主要瓶颈。 针对含 C 共晶高熵合金强度不足的问题，以 FCC+M4C3 型 CoFeNi2(V2.5C)0.2 共晶高熵合金为基体，通过添加 Al 元素改变凝固路径，设计制备了 Al0.3CoFeNi2(V2.5C)0.2 过共晶高熵合金。 该合金由初生 M4C3 碳化物相和 FCC 固溶体相组成，在保持伸长率(10.7%±1.1%)基本不变的同时，屈服强度和抗拉强度分别提升 37%和 21%，达到(482±22) MPa 和(918±27) MPa。 通过经典强化模型并结合微观组织表征(SEM、XRD、EBSD)揭示了其强韧化机制：强度提升主要源于 Al 的固溶强化与初生碳化物的析出强化，提升了加工硬化率，延缓了塑性失稳，实现了强韧协同。Eutectic high-entropy alloys (EHEAs) have garnered extensive attention in the field of materials science because of their excellent mechanical properties and superior castability. Among them, C-containing eutectic high-entropy alloys represent a novel design system developed in recent years. Although they exhibit good plasticity, their low yield strength remains a bottleneck that restricts their engineering applications. To address the insufficient strength of carbon-containing eutectic high-entropy alloys, an FCC+M4C3-type CoFeNi2(V2.5C)0.2 eutectic high-entropy alloy was utilized as the matrix. By adding Al to alter the solidification path, an Al0.3CoFeNi2(V2.5C)0.2 hypereutectic high-entropy alloy was designed and fabricated. The alloy consists of a primary M4C3 carbide phase and an FCC solid solution phase. While essentially unchanged elongation (10.7%±1.1%) is maintained, the yield strength and tensile strength increases by 37% and 21%, reaching (482 ±22) MPa and (918 ±27) MPa, respectively. Through classical strengthening models combined with microstructural characterization (SEM, XRD, EBSD), the strengthening and toughening mechanisms are elucidated: the strength enhancement primarily originates from the solid solution strengthening effect of Al and the precipitation strengthening from the primary carbides, which enhances the work hardening rate, delays plastic instability, and achieves asynergistic improvement in strength and ductility.