Preparation of high-strength (Ta,W)C solid-solutions by spark plasma sintering

(Ta,W)C bulks were prepared by spark plasma sintering. Densification kinetics and solid-solution formation kinetics were performed on the powder mixtures using TaC and W powders. The as-received tungsten powder had a spherical shape and rather coarse size. By using the crushed and as-received powder, it can be suggested that sintering at 2000 degrees C limits the reaction volume to 3-6 mu m and hence allows forming a complete solid-solution using finer powders. The lattice parameter, hardness, toughness, and strength were investigated as a function of the TaC content. The flexural strength of the (Ta,W)C ceramic bulks was investigated up to 2000 degrees C and it was found that the maximum strength was for the 60 mol.% TaC composition. Strength as a function of the temperature tended to increase up to 1200 degrees C followed by a gradual decrease to 2000 degrees C. When the TaC was reinformed by coarse W spheres, the flexural strength monotonically decreased from 570 MPa at room temperature to 220 MPa at 2000 degrees C.

Automated summary

(Ta,W)C ceramic bulks were prepared by spark plasma sintering. The densification kinetics and solid-solution formation kinetics of the powder mixtures using TaC and W powders were studied. It was found that sintering at 2000 degrees C limits the reaction volume and allows forming a complete solid-solution using finer powders. The flexural strength of the (Ta,W)C ceramic bulks was investigated as a function of the TaC content, and the maximum strength was found for the 60 mol.% TaC composition. Strength increased up to 1200 degrees C and then gradually decreased to 2000 degrees C. When TaC was reinformed by coarse W spheres, the flexural strength decreased from 570 MPa at room temperature to 220 MPa at 2000 degrees C.