Effect of Mo and Hf on the mechanical properties and microstructure of Nb–Ti–C alloys

Effect of carbon on the microstructures and mechanical properties of as cast Nb-base alloy

“…For example, some defects such as dislocations and stacking faults were observed in primary carbides (Nb/Ti: ∼1) in as-cast NbTiC alloys [16] but not in the present alloys (Ti-rich carbide); it was easier to find secondary carbides (Nb/Ti: ∼1) with significant twin deformation in compressed NbTiC samples [16] compared to secondary carbides (Ti-rich) in the present study. Ta addition improved the plastic deformation of WC in WC-Co composite [22].…”

“…10) illustrates this. It should be noted that it was easier to find carbides with significant twin deformation in our previous work on NbTiC alloys [16]. This may be related to the following factors: the small carbides in the present alloys are not so long as in the NbTiC alloys; the compositions of the carbides (Ti/Nb: ∼1 in the NbTiC vs. ∼2-3 in present alloys) may influence their plasticity.…”

Influence of Al on microstructural evolution and mechanical behaviour of Nb–9Ti–8C alloys

“…According to Nb-C and Ti-C binary phase diagram [20,22], carbide was in a state of carbon deficiency because of the sufficient cooling rate and the limited atomic diffusion during an actual solidification process. And the most stable carbide is TiC in Nb-Ti-C system.…”

“…Common approaches to enhance the strength of Nb-based alloy include multi-element solution strengthening [10-12] and precipitation strengthening [13-16]. Recently, the main research focus is the effect of Ti, Al, C elements on phase composition, structure and mechanical properties of Nb-based alloys [14, 17-20]. Ti addition can improve tensile strength and toughness.…”

“…Excessive Al and C elements lead to the precipitation of brittle Nb 3 Al and carbide phases. The hard-brittle Nb 3 Al and carbide phase provide outstanding strength at room temperature and evaluated temperature, however, these phases decrease the fracture toughness at room temperature [15,16,20]. In addition, Ti and Al addition can improve the oxidation resistance of Nb alloys [17,19].…”