Cr含量对铸态和热处理后AlCr_(x)CuFeNi高熵合金微观组织和硬度的影响

Effect of Cr content on microstructure and hardness of as-cast and heat treated AICr_(x)CuFeNi high-entropy alloys

采用电弧熔炼工艺制备了AlCr_(x)CuFeNi(x=0,1.0,2.0)高熵合金(记为Cr_(0)、Cr_(1.0)和Cr_(2.0)合金),研究了Cr含量对高熵合金铸态和600℃热处理后的微观组织和显微硬度的影响。结果表明,铸态条件下,Cr_(0)合金的物相结构主要由富Fe、Ni的FCC固溶体相和AlCu3相组成,而Cr_(1.0)和Cr_(2.0)合金均由富Cu的FCC2相、富Cr、Fe的BCC相和AlNi相组成。600℃热处理后,高熵合金的物相结构基本未发生改变,具有良好的物相稳定性,且合金的元素偏析程度显著改善。Cr_(0)合金铸态显微硬度为348HV10,600℃热处理后略增至370HV10。随Cr含量提高,高熵合金的硬度随之增加,其中Cr_(2.0)合金铸态和600℃热处理后的显微硬度最高,分别达到435和462HV10。热处理后合金硬度增加主要与固溶强化、析出强化和细晶强化机制有关。

AlCr_(x)CuFeNi(x=0,1.0,2.0)high-entropy alloys,which named as Cr_(0),Cr_(1.0)and Cr_(2.0),was prepared by using arc melting technology.The effect of Cr content on microstructure and microhardness of the as-cast high-entropy alloys and after heat treatment at 600℃was studied.The results indicate that the phase structure of the as-cast Cr_(0)alloy is mainly composed of(Fe,Ni)-rich FCC solid solution phase and AICus phase,while both Cr_(1.0)andCr_(2.0)alloys are composed of Cu-rich FCC2 phase,(Cr,Fe)-rich BCC phase and AINi phase.After heat treatment at 600℃,the phase structure of the alloy remains largely unchanged,indicating good phase stability,meanwhile,the element segregation degree of the high-entropy alloy is significantly improved.The microhardness of the as-cast Cr_(0)alloy is 348 HV10,which slightly increases to 370 HV10 after heat treatment at 600℃.As the Cr content increases,the hardness of the high-entropy alloys also increases,and the microhardness of the as-castCr_(2.0)alloy and after heat treatment at 600℃is the highest,reaching 435 and 462 HV10,respectively.The increase in hardness of the high-entropy alloys after heat treatment is mainly related to the mechanisms of solid solution strengthening,precipitation strengthening and fine-grained strengthening.