冷轧退火对(FeCoNiCr)_(100-x-y)Al_(x)Ti_(y)高熵合金组织和力学性能的影响

Effects of cold rolling and heat treatment on microstructure and mechanical properties of(FeCoNiCr)_(100-x-y)Al_(x)Ti_(y)high-entropy alloy

使用真空感应悬浮熔炼炉制备了(FeCoNiCr)_(100-x-y)Al_(x)Ti_(y)高熵合金,并对合金(FeCoNiCr)_(93)Al_(5)Ti_(2)进行冷轧及热处理,利用扫描电镜(SEM)、电子背散射衍射仪(EBSD)和X射线衍射仪(XRD)分析了合金的组织结构。结果表明:合金在铸态和退火态相组成均为面心立方相(FCC),(FeCoNiCr)_(93)Al_(5)Ti_(2)合金经冷轧50%及热处理后,晶粒尺寸产生明显细化,同时大量退火孪晶在晶内形成,晶界处有块状微米级L12相不连续析出,在晶粒内有纳米尺度L12相连续析出。相比于铸态FeCoNiCr合金,冷轧50%热处理后的(FeCoNiCr)_(93)Al_(5)Ti_(2)屈服强度由145 MPa提升到481 Mpa,提升了231.7%;抗拉强度由456 MPa到871 MPa,提升了91.0%;断后延伸率由75.4%到59.3%,仅下降16.1%。优异的综合力学性能归因于细晶强化、L12相的析出强化、大量退火孪晶的形成。

The(FeCoNiCr)_(100-x-y)Al_(x)Ti_(y)high-entropy alloy was prepared using a vacuum induction levitation melting furnace,and the(FeCoNiCr)_(93)Al_(5)Ti_(2)was cold-rolled and heat-treated.The microstructure of the alloy was analyzed using scanning electron microscopy(SEM),electron backscatter diffraction(EBSD),and X-ray diffraction(XRD).The results showed that the alloy is face centered cubic(FCC)in both cast and annealed phases.(FeCoNiCr)_(93)Al_(5)Ti_(2)alloy after cold rolled 50%and heat treatment,the grain size is significantly refined,and a large number of annealing twins are formed in the crystal,massive micron L12 phase at the boundary,and nanoscale L12 phase in the grain.Compared to the as cast FeCoNiCr alloy,the yield strength increased from 145 MPa to 481 MPa,an increase of 231.7%;The tensile strength increased by 91.0%from 456 MPa to 871 MPa;The elongation after fracture increased from 75.4%to 59.3%,a decrease of only 16.1%.The excellent comprehensive mechanical properties are attributed to the fine grain strengthening,the precipitation hardening of the L12 phase,and the formation of a large number of annealing twins.