含Gd亚稳FeMnCoCrNi高熵合金塑性诱发相变与室温微蠕变研究

Study on plasticity-induced phase transformation and room temperature micro-creep of Gd-containing FeMnCoCrNi metastable high-entropy alloy

高熵合金因具有优异的力学性能及广阔的组元选配空间而日益受到关注。本文研究了亚稳态Fe_(38-x)Mn_(30)Co_(15)Cr_(15)Ni_(2)Gd_(x)(x=0,0.1,0.2)高熵合金在不同预应变准静态压缩过程中由塑性诱发的面心立方(face-centered cubic,FCC)向密排六方(hexagonal close-packed,HCP)的相转变行为,测定了FCC相和HCP相的纳米压痕硬度和弹性模量,在此基础上比较研究了其室温微蠕变变形特性。结果表明,增加Gd含量和压缩预应变可促进相变,硬质HCP相的纳米压痕硬度和弹性模量显著高于FCC相;Gd的添加可提高未预压缩单相FCC合金的抗蠕变能力,相同压缩预应变下,含Gd合金经预压缩后FCC相、HCP相在相同载荷下的蠕变速率明显降低,且后者表现出更优的抗蠕变特性。对高熵合金组元进行非等原子比设计,通过塑性诱发相变引入新的固溶体相,可为提高合金的综合力学性能尤其是蠕变抗力提供有价值的技术途径。

High entropy alloys(HEAs)have attracted increasing attention due to their excellent mechanical properties and broad space for component selection.The present study investigated plasticity-induced face-centered cubic(FCC)to hexagonal close-packed(HCP)phase transformation behavior of metastable Fe_(38-x)Mn_(30)Co_(15)Cr_(15)Ni_(2)Gd_(x)(x=0,0.1,0.2)HEAs after subjected to compressive deformation with different strains.Nanoindentation hardness and elastic modulus of the FCC and HCP phases were examined.A comparison was conducted for room temperature micro-creep deformation characteristics of the two solid solution phases.The results show that the phase transformation is promoted via increasing Gd content and compression pre-strain.The formed hard HCP phase exhibits much higher nanoindentation hardness and elastic modulus than those of the FCC phase.Gd addition improves creep resistance of the single-phase FCC alloy without pre-compression and simultaneously leads to a remarkable reduction in creep strain rates at a given load of the FCC and HCP phases under an identical compression pre-strain.Moreover,the HCP phase shows a higher creep resistance,which implies that introducing a new solid solution phase via plastic deformation in non-equiatomic metastable HEAs is an practical technological approach to enhance their comprehensive mechanical properties,especially the resistance against creep deformation.