Thermomechanical properties of TiC particle-reinforced tungsten composites for high temperature applications

Tungsten and tungsten alloys are widely used in high temperature environments where arc ablation or mechanical deformation and damage are the main sources of materials failure. For high temperature critical applications in thermomechanical environments, however, the low strength limits the use of tungsten and tungsten alloys. Hence, new tungsten based materials with good high temperature thermomechanical properties need to be developed in order to extend the use of tungsten. TiC particle-reinforced tungsten based composites (TiCp/W) were fabricated by hot pressing at 2000 degreesC, 20 MPa in a vacuum of 1.3 x 10(-3) Pa. The composites were examined with respect to their thermophysical and mechanical properties at room temperature and at elevated temperature. Vickers hardness and elastic modulus increased with increasing TiC content from 0 to 40 vol.%. The highest flexural strength, 843 MPa, and the highest toughness, 10.1 MPa m(1/2), of the composites at room temperature were all obtained when 20 vol.% TiC particle were added. As the test temperature rose, the flexural strength of the TiCp/W composites firstly increased and then decreased, except in the monolithic tungsten. The highest strength of 1155 MPa was measured at 1000 degreesC in the composite containing 30 vol.% TiC particles. The strengthening effect of TiC particles on the tungsten matrix is more significant at high temperatures. With the addition of TiC particles, the thermal conduction of tungsten composites was drastically decreased from 153 W m(-1) K-1 for monolithic W to 27.9 W m(-1) K-1 for 40 vol.% TiCp/W composites, and the thermal expansion was also increased. The new composites are successfully used to make high temperature grips and moulds. (C) 2003 Elsevier Science Ltd. All rights reserved.