碳化硼对高熵合金结构及性能的影响

Effect of B4C on microstructure and properties of high-entropy alloy

采用微波烧结工艺制备B4C/FeCoNiCrAl与B4C/FeCoNiCrCu高熵合金基复合材料,研究了不同含量的B4C对FeCoNiCrAl、FeCoNiCrCu高熵合金组织结构和性能的影响。结果表明:B4C的添加一定程度上增加了基体合金的晶格畸变,合金微观组织由高熵合金基底区、碳化硼分解生成的硼化物区和碳化物区3部分构成。体心立方结构的FeCoNiCrAl高熵合金中硼化物为针状,面心立方结构FeCoNiCrCu高熵合金中硼化物组织为块状,这与合金体系中的原子尺寸差相关。B4C可显著提高合金的强度和硬度,塑性略有下降。4%B4C/FeCoNiCrAl合金复合材料具有最高的硬度和压缩强度值,分别为627.1HV0.5和1836MPa,但是塑性较差,压缩比仅为11%;而4%B4C/FeCoNiCrCu合金复合材料硬度与强度仅为249.3HV0.5与1413MPa,低于4%B4C/FeCoNiCrAl复合材料,但塑性较好,压缩比可达35%。

High entropy alloy matrix composites B4C/FeCoNiCrAl and B4C/FeCoNiCrCu were prepared by microwave sintering process.The effects of different contents of B4C on the microstructure and properties of high-entropy alloy were investigated.The results show that the addition of B4C increases the lattice distortion of matrix alloy to a certain extent.The microstructure of the alloy consists of a high-entropy alloy basement region,a boride region formed by decomposition of boron carbide,and a carbide region.The boride of the body-centered cubic FeCoNiCrAl high-entropy alloy is needle-like,and the high-entropy alloy boride structure of the face-centered cubic structure FeCoNiCrCu is block-shaped,which is related to the atomic size difference in the alloy system.B4C can significantly improve the strength and hardness of the alloy,and the plasticity decreases slightly.The 4%B4C/FeCoNiCrAl alloy composite presents the highest hardness and compressive strength values of 627.1 HV0.5 and 1836 MPa,respectively,but the plasticity is poor,and the compression ratio is only 11%.The hardness and strength of the 4%B4C/FeCoNiCrCu alloy composite are only 249.3 HV0.5 and 1413 MPa,which are lower than that of 4%B4C/FeCoNiCrAl alloy composite,but the plasticity is good and the compression ratio can reach 35%.