定向凝固法制备高强塑性多级异构共晶高熵合金

Hierarchically Heterogeneous Eutectic High-entropy Alloy with High Strength and High Ductility Fabricated by Directional Solidification

采用定向凝固和常规电弧熔炼两种方法制备AlCoCrFeNi2.1共晶高熵合金。运用扫描电子显微镜、电子背散射衍射仪及拉伸试验机对两种方法制备的共晶高熵合金的显微结构、拉伸性能及其变形机制进行对比研究。结果表明:采用常规电弧熔炼法制备的AlCoCrFeNi2.1共晶高熵合金具有精细规则的共晶层片结构,抗拉强度为1.05 GPa,均匀延伸率为16%;采用定向凝固法制备的共晶高熵合金具有多级异质共晶结构,不仅具有更高的抗拉强度(1.16 GPa),同时展现出优良的拉伸塑性(均匀延伸率为25%)。多级异构共晶高熵合金具有更突出的协调变形和应变硬化能力,从而使其具有优异的强塑性匹配。

AlCoCrFeNi2.1 eutectic high-entropy alloys were prepared by directional solidification and conventional arc melting,respectively.The microstructure,tensile properties and deformation mechanism of the eutectic high-entropy alloys prepared by the two methods were investigated by scanning electron microscope,electron backscatter diffraction and tensile testing machine.The results showed that the AlCoCrFeNi2.1 eutectic high-entropy alloy prepared by conventional arc melting process had a fine and regular eutectic lamellar structure with tensile strength of 1.05 GPa and uniform elongation of 16%;the eutectic high-entropy alloy prepared by directional solidification method had a hierarchically heterogeneous eutectic structure with higher tensile strength(1.16 GPa)and superior tensile plasticity(uniform elongation of 25%).The hierarchically heterogeneous eutectic high-entropy alloy had more outstanding coordinated deformation and strain hardening capability,thus resulting in its excellent matching of strength and plasticity.