Microstructure and mechanical properties of AlNbTiVZr system refractory high entropy alloys

To obtain refractory high entropy alloys (REHAs) with reasonable microstructure and excellent properties, the effects of Zr on the microstructure and mechanical properties of Al0.5NbTiV2Zrx and Al0.5Nb0.5TiV2Zrx (x = 0.5, 1.0, 1.5) RHEAs were investigated. The results show that Al0.5NbTiV2Zrx and Al0.5Nb0.5TiV2Zrx alloys have obvious identical changes with the change of Zr content. BCC structure is matrix phase, and the second phase is Laves phase. With the increase of Zr content, the BCC matrix phase decreases and the volume fraction of the Laves phase increases. Meanwhile, at room temperature, the compressive properties decrease with the increase of the volume fraction of the second phase. When the compression test temperature increases to 1073 K, the strength of the alloy decreases and its deformability increases. The yield strength of Al0.5NbTiV2Zr0.5 and Al0.5Nb0.5TiV2Zr0.5 alloys decreased to 635 MPa and 656 MPa respectively, and the compressive strain still exceeded 50 %. The ductile brittle transition temperature appears between 873 K and 1073 K, which is induced by the dislocation movement of the matrix. The mechanical properties of Al0.5Nb0.5TiV2Zr0.5 alloy at room temperature and high temperature exhibits the best mechanical properties.