Interstitial Strengthening of a Cast and Wrought Ni-Based Heavy Density Matrix Alloy by Carbon Addition

An interstitial strengthened Ni-based heavy-density matrix alloy (Ni-37W-19Co-xC) was prepared by conventional casting and wrought metallurgy techniques, and the effect of carbon addition on the microstructure, mechanical properties, and deformation behaviors was investigated. The results demonstrated that both carbon-doped and carbon-free alloys exhibit a single face-centered cubic structure, whereas the interstitial carbon atoms were fully dissolved into the matrix without any ceramic phases precipitated. With the benefit of interstitial strengthening, the 0.021 wt.% carbon-doped alloy exhibited an exceptional combination of strength and ductility, with a yield strength of 420 MPa, tensile strength of 1014 MPa, and large deformability of 65% strain at ambient temperature. Dislocation substructure hardening and deformation twinning produced a multi-stage strain-hardening behavior, which delayed the shrinkage and improved the strength, resulting in an excellent combination of strength and ductility.