The influences of Cr3C2 addition on the phase formation and mechanical properties of (Zr,Ti,Nb,Ta,Hf)C

Abstract

The influences of Cr₃C₂ addition on phase formation, microstructures and mechanical properties of (Zr,Ti,Nb,Ta,Hf)C prepared from binary carbides mixtures by spark plasma sintering were studied. The introduction of 4/3 mol.% Cr₃C₂ significantly lowered the minimum temperature for uniform high-entropy phase (Zr,Ti,Nb,Ta,Hf)C from 2200 °C for to 1900 °C. The lower solubility limit of Cr in (Zr,Ti,Nb,Ta,Hf,Cr)C results in excessive Cr₃C₂-based carbides, which tends to segregate along grain boundaries at higher sintering temperatures while locate at triple junctions at lower sintering temperatures. High mechanical strength of 599 MPa were obtained when 4/3 mol.% Cr₂C₃ was added and sintered at 1900 °C. The fine grain size and Cr₃C₂-based carbides are responsible for the high mechanical properties. More Cr₂C₃ addition results in lower mechanical properties due to excessive Cr₃C₂-based carbides.