【摘要】 采用真空电弧熔炼工艺制备了不同Al含量的Al_xMo_0.5NbTiVSi_0.2（x=0.5,0.8,1.0,摩尔比）难熔高熵合金。研究了合金的相组成、微观组织、密度和力学性能。结果表明，Al_xMo_0.5NbTiVSi_0.2高熵合金的微观组织为典型的树枝晶结构，均由BCC固溶体相和M₅Si₃金属间化合物相组成。Al含量的增加并未使得合金的相组成发生改变。合金BCC基体相富集Al、Mo和V元素，M₅Si₃相富集Ti和Si元素，Nb元素在两相中分布较为均匀。随Al含量增加，合金的密度从6.18 g/cm³降至5.86 g/cm³,硬度提升了13.7%,压缩屈服强度增加约332 MPa,增幅达到37%,抗压强度从1 073 MPa提高到1 457 MPa,断裂应变从13.6%增加到14.4%。合金力学性能的提升主要是通过固溶强化、细晶强化和第二相强化机制实现的。更多还原

【Abstract】 Al_xMo_0.5NbTiVSi_0.2（x=0.5, 0.8, 1.0, molar ratio） refractory high entropy alloys with different Al contents were fabricated by vacuum arc melting. The phase composition, microstructure, density and mechanical properties of the alloy were investigated. The results indicate that the Al_xMo_0.5NbTiVSi_0.2 high entropy alloys are characterized by dendritic structure, which are composed of BCC solid solution matrix phase and M₅Si₃ intermetallic phase. The phase composition of the alloy has little change with the increase of Al content. Al, Mo and V elements are enriched in BCC matrix phase, while Ti and Si elements are enriched in M₅Si₃ phase, and Nb elements are evenly distributed in both phases. With the increase of Al content, the density of the alloy is decreased from 6.18 g/cm³ to 5.86 g/cm³, and the hardness is increased by 13.7%. The compressive yield strength is increased by nearly 332 MPa（37%）, and the compressive strength is increased from 1 073 MPa to 1 457 MPa, while the fracture strain is increased from 13.6% to 14.4%. The enhancement of mechanical properties are mainly attributed to solid solution strengthening, fine grain strengthening and second phase strengthening mechanisms.更多还原