退火处理对粉末冶金CoCrFeNiC_(0.05)高熵合金热轧板显微组织和力学性能的影响

Effects of annealing on microstructure and mechanical properties of powder metallurgy hot rolled CoCrFeNiC_(0.05)high-entropy alloy sheet

以Cr、Co、Fe、Ni单质块体和Cr_(3)C_(2)为原料,采用气雾化法制备预合金粉,通过热等静压法制备CoCrFeNiC_(0.05)高熵合金,对合金进行热轧和退火处理,结合X射线衍射、金相显微镜、扫描电子显微镜、透射电子显微镜、电子背散射衍射、硬度测试和拉伸性能测试等手段,研究退火处理对粉末冶金CoCrFeNiC_(0.05)高熵合金热轧板显微组织和力学性能的影响。结果表明:热轧变形后,合金晶粒形态由热等静压的等轴状转变为条带状,织构组态以F织构为主,晶内存在孪晶和亚微米级Cr_(23)C_(6)碳化物。经800℃退火处理后,合金发生完全再结晶。热轧结合中温退火(500℃)是获得具有良好综合力学性能CoCrFeNiC_(0.05)高熵合金的有效途径,合金的屈服强度为961 MPa,抗拉强度为1023 MPa,伸长率为13.6%。

The pre-alloyed powder was prepared by gas atomization method with Cr,Co,Fe,Ni simple substance and Cr_(3)C_(2) as raw materials.CoCrFeNiC_(0.05)high-entropy alloy was prepared by hot isostatic pressing,and the alloy was hot rolled and annealed.The effects of annealing on the microstructure and mechanical properties of powder metallurgy hot rolled CoCrFeNiC_(0.05)high-entropy alloy sheet were systematically studied by X-ray diffraction,optical microscope,scanning electron microscope,transmission electron microscope,electron backscatter diffraction,Vickers hardness,and tensile testing.The results show that the grains are equiaxed in hot isotactic pressed alloy but transform to elongated morphology after hot rolling.The hot rolled sheet exhibits a strong F-type texture,and twins and submicron Cr_(23)C_(6)typed carbide are observed.After annealing treatment at 800℃,the alloy undergoes complete recrystallization.Hot rolling combining with moderate temperature annealing(500℃)is an effective approach to achieving good comprehensive mechanical properties for CoCrFeNiC_(0.05)high-entropy alloy,with yield strength of 961 MPa,tensile strength of 1023 MPa,and elongation of 13.6%.