Effect of vanadium addition on the microstructure and properties of AlCoCrFeNi high entropy alloy

• The AlCoCrFeNiVx high entropy alloys were prepared by arc melting.
• The compressive strength and plastic strain was as high as 3297.8 MPa and 26.8%.
• V element can reduce elements segregation and homogenize the microstructure.
• A transition from ferromagnetic to paramagnetic happens in this alloy system.

The purpose of this study is to investigate the effects of vanadium addition on the microstructure and mechanical properties of AlCoCrFeNiVx (x values in molar ratio, x = 0, 0.2, 0.5, 0.8, 1.0) alloys. All the alloys were found to display a crystalline structure of simple body centered cubic (BCC). For AlCoCrFeNi and AlCoCrFeNiV0.2 alloys, Cr and Fe elements segregated to the center of grain while Al and Ni elements segregated to the rest areas. With the increase of V content exceeding to x = 0.5, the homogenized polycrystalline grain can be obtained. For AlCoCrFeNiV0.2 alloy, the compressive strength and plastic strain were as high as 3297.8 MPa and 26.8%, respectively, which were rare in high entropy alloys to date. The fine nanoscale spinodal decomposition microstructure was a key factor for the high fracture strength of AlCoCrFeNiV0.2 alloy. The values of Vickers hardness increased from HV534 to HV648.8 with the increase of V content. The solid-solution strengthening of the body centered cubic matrix was found as the main factor that strengthened the alloys. With the increase of V contents from x = 0 to x = 1.0, the transformation of ferromagnetic behavior to paramagnetic behavior takes place.