基于成分与力学性能调控的NbTiMoVHf(Zr)Si系难熔高熵合金优化

Optimization of NbTiMoVHf(Zr)Si system refractory high-entropy alloys based on composition and mechanical properties control

高温力学性能优异的难熔高熵合金在航空发动机热端部件制造中展示出广阔的应用前景。首先,采用真空电弧熔炼法制备了20种NbTiMoVHf(Zr)Si系难熔高熵合金,并通过维氏硬度和拉伸性能测试确定了具有较好力学性能的合金样品,随后利用X射线衍射和电子背散射衍射等研究了其微结构特征。结果表明:NbTiMoVZrSi系高熵合金的力学性能更优,维氏硬度可达723 HV,抗拉强度可达219 MPa;随着Si含量增加,合金的晶粒尺寸减小,析出更多硬质硅化物,且硬度最高的样品小角度晶界含量较高。

The refractory high-entropy alloys with excellent high temperature mechanical properties show a great potential in the manufacturing of hot end components of aeroengines.First,20 kinds of NbTiMoVHf(Zr)Si refractory high-entropy alloys were prepared by vacuum arc melting,and the alloy samples with good mechanical properties were determined by Vickers hardness and tensile properties tests.Then,their microstructure features were studied by X-ray diffraction and electron backscatter diffraction technique.The results show that the NbTiMoVZrSi high-entropy alloy has higher mechanical properties.The Vickers hardness and the tensile strength can reach 723 HV and 219 MPa,respectively.With the increase of Si content,the grain size of the alloy decreases and more hard silicides are precipitated.The sample with the highest hardness has relatively high proportion of low angle grain boundaries.