Thermomechanical behaviour of WC-W2C composites at first wall in fusion conditions

Metallic tungsten and tungsten carbide are some of the more relevant candidates proposed because of their high melting point, shielding capabilities and resistance to neutron damage. In this work, the microstructural and high temperature mechanical characterization of WC matrices with additions of 10, 20 and 50 vol% of W, dispersed by colloidal processing routes and sintered by Spark Plasma Sintering (SPS), are presented. Flexural elastic modulus, fracture strength and SENB toughness has been determined by the three-point bending tests at 600, 800, 1000 and 1200 degrees C. Microstructural analysis shows that after SPS all the metallic tungsten has reacted to form W2C, and sintering process is able to stabilize phases corresponding to temperatures higher than achieved as a consequence of the additional energy provided by the method. Mechanical results indicated that resistance of all materials increases as the operating temperature increases. Furthermore, remarkably great results are obtained for the composition with 10 and 20 vol% of W. This macroscopic behaviour has been related to the microstructural decomposition of the metastable W2C, to WC and W, as temperature for the bending tests approach to the equilibrium temperature (1250 degrees C). It was found that the presence of metallic tungsten in the final microstructure could be the responsible of the plastic behaviour of the tested pieces at 1200 degrees C and the doubled value of the toughness.

Automated summary

In this study, WC matrices with additions of 10, 20, and 50 vol% of tungsten dispersed by colloidal processing routes and sintered by Spark Plasma Sintering (SPS) were characterized for their microstructure and high temperature mechanical properties. The presence of metallic tungsten in the final microstructure was found to be responsible for the plastic behavior and increased toughness of the tested pieces at 1200 degrees C. The mechanical results indicated that the resistance of all materials increased with increasing operating temperature, with the composition containing 10% and 20% tungsten exhibiting the best performance.