Nanoindentation mechanical properties of TiB₂-TiC-TiNiFeCrCoAl high-entropy alloys cermet: A comparison study with WC-Co

This paper studies the mechanical properties including hardness and elastic modulus of a novel TiB₂-TiC-TiNiFeCrCoAl high-entropy alloys (HEA) cermet using the nanoindentation method. For comparison, a commercial WC-Co cemented carbide was also studied. The results indicate that, under the loads between 4mN and 10mN, the TiB₂-TiC-HEA cermet has higher hardness in the range of ~28.4–33.8GPa (compared with ~22.3–26.2GPa for the WC-Co sample) however lower moduli in the range of ~416.9–456.6GPa (compared with ~466.0–516.5GPa for the WC-Co sample). Significant indentation size effects can be observed for both samples. Grains and phases influence the mechanical properties as well. With selected indentation positions on individual grains, under a load of 4mN, the mechanical properties of the TiB₂-TiC-HEA sample are scattered due to the multiple phases (TiC and TiB₂) and different facets. Among such results, there are two groups which have similar properties within each group. For comparison, the WC-Co sample shows two groups of results on the individual grains, which are correlated to the different facets of WC. Compared between these two samples, the hardness of the two groups of TiB₂-TiC-HEA(~36.6 ± 2.8GPa and 30.2 ± 2.6GPa), are also higher than the two groups of WC-Co (~30.7 ± 2.5GPa and 25.0 ± 3.9GPa).