Y添加对CoCrFeMnNi高熵合金组织及力学性能的影响

Effects of Y Addition on Structure and Mechanical Properties of CoCrFeMnNi High Entropy Alloys

通过向FCC结构的CoCrFeMnNi高熵合金中添加Y来改善其强度,系统研究了Y含量对(CoCrFeMnNi)_(100-x)Y_(x)(x=0、1、2、3、4,摩尔比)高熵合金微观组织与力学性能的影响。结果表明,随着x增加到2,合金中有富Y和Ni的HCP结构的第二相生成,呈长条状;当x=4时,HCP相呈矩形镂空网状且规律分布,并分布有黑色富Y金属间化合物。随着Y含量增加,第二相体积分数逐渐增加。Y的添加增加了合金的原子尺寸差及熵焓比,有助于第二相的形成。力学性能测试表明,压缩强度及显微硬度随着Y含量的增加逐渐升高,(CoCrFeMnNi)_(96)Y_(4)合金的屈服强度为521 MPa,显微硬度(HV)为321.6,较基体合金CoCrFeMnNi(187 MPa,160.3)分别增加了178.6%、100.6%。第二相体积分数增加是导致合金强度及硬度提升的主要原因。

The effects of Y addition on the microstructure and mechanical properties of(CoCrFeMnNi)_(100-x)Y_(x)(x=0、1、2、3、4)high entropy alloys were investigated.The results indicate that the second phase of HCP structure rich in Y and Ni is formed with the increase of x to 2,presenting a long strip shape.When x=4,the HCP phase is distributed in a rectangular network shape,with the black Y-rich intermetallic compounds distributed.With the increase of Y content,the volume fraction of the second phase is increased gradually.The addition of Y promotes the atomic size difference and enthalpy-entropy ratio of the alloy,contributing to the formation of the second phase.The mechanical properties reveal that the compressive strength and microhardness are gradually increased with the increase of Y content.The yield strength and microhardness of(CoCrFeMnNi)_(96)Y_(4) alloy are 521 MPa and 321.6 HV,which are increased by 178.6%and 100.6%,respectively,compared with those of the matrix CoCrFeMnNi alloy(187 MPa,160.3 HV).The enhancement of the strength and hardness of the alloys is mainly attributed to the increase of the volume fraction of the second phase in the entropy alloys.