Effect of carbon and tungsten content on the phase equilibria, microstructure, and mechanical properties of (Nb,W)C-Ni cermets

With the assistance of thermodynamic simulation, the NbC-Ni based cermets with different W and C additions were designed and sintered in liquid state at 1390 degrees C for 90 min in vacuum. By controlling the carbon and tungsten content, (Nb,W)C-Ni based cermets were prepared with varied phase constitution, microstructure, and mechanical properties. The microstructure, composition of phases, grain size, and equilibrium phases were investigated using scanning electron microscopy, electron probe microanalysis, EBSD, and X-ray diffraction. The simulation reasonably predicted the experimentally observed phase constitutions. Depending on the additions, detailed analysis indicated that the cermets were composed of either a combination of cubic (Nb,W)C solid solution and Ni alloy binder or with an additional carbon-deficient phase. Furthermore, mechanical analysis showed a strong dependence of its mechanical properties (Vickers hardness, indentation toughness, and flexural strength) on the phases and NbC grain size.

Automated summary

By using thermodynamic simulation, NbC-Ni based cermets with different W and C additions were designed and sintered in liquid state, resulting in varied phase constitution, microstructure, and mechanical properties. Microscopic analysis revealed the presence of cubic (Nb,W)C solid solution, Ni alloy binder, and carbon-deficient phase in the cermets. Additionally, mechanical properties such as hardness, toughness, and strength were found to be influenced by the phases and NbC grain size.