The effect of sintering conditions and ZrN volume fraction on the mechanical properties of spark plasma sintered W/ZrN composites

Abstract

In an effort to improve the room temperature mechanical properties of tungsten, W/ZrN composites were fabricated by high energy ball milling followed by spark plasma sintering at temperatures in a range of 1200-1700 degrees C under a pressure of 50 MPa. The effects of sintering conditions and ZrN volume fraction on the mechanical properties of the W/ZrN composites were studied and the results were compared to the properties of monolithic tungsten. The grain size of monolith tungsten and W/ZrN composites was found to increase with an increase in sintering temperature and time. In the case of the W/ZrN composites, ZrN particles led to an increase in the compressive strength of tungsten and a decrease in grain size. The increase in compressive strength of the composites was attributed to a reinforcement effect of ZrN particles as well as grain size refinement according to the Hall-Petch relation. Compressive strength of the composites increased with increasing ZrN content while the flexural strength decreased for samples with ZrN content exceeding 10 vol.%. This was attributed to the effects of ZrN agglomeration within the tungsten matrix. (c) 2012 Elsevier B.V. All rights reserved.