Microstructure and mechanical properties of lightweight (AlNbTiVCr)100-C high entropy alloys by carbide strengthening

Abstract

• A new type of lightweight (AlNbTiVCr) 100- x C x high entropy alloy were investigated. • The HEAs have BCC Structure and the second phase due to the introduction of carbon. • HEAs exhibit good specific strength and room temperature excellent plasticity. To improve the mechanical properties and decrease the alloy density of AlNbTiVCr high entropy alloy (HEA), (AlNbTiVCr) 100- x C x ( x =0-3.5 at.%) HEAs were prepared, the effect of alloying element Carbon on the microstructure and mechanical properties of HEAs were studied. With the addition of carbon, Laves phase rich in (Cr, Nb) and second phase (TiC) gradually appear in the alloys, and the volume fraction of TiC increases with the increase of carbon content. The addition of carbon significantly improves the strength and plasticity of the alloys. When x =1.5 at.%, the compressive strength and fracture strain reach their maximum values (2.03 GPa and 13%). With the further increase of carbon content, a large number of second phases are formed and aggregated, which worsens the mechanical properties of the alloy. The significant improvement of mechanical properties is attributed to the combination of second phase strengthening and solid solution strengthening.