Thermal shock resistance and toughening mechanism of W/Ta and W/TiN/Ta laminated composites

The brittleness of tungsten (W) is a significant limitation on its widespread applications as a high-temperature structural material. Laminated composite technology proved to be an effective method to improve the toughness of W. In this work, W/Ta and W/TiN/Ta laminated composites were prepared by spark plasma sintering (SPS) to overcome the brittleness of W. The toughening properties of the W/Ta and W/TiN/Ta laminated composites were evaluated by electron beam thermal shock and laser thermal diffusivity testing. The toughening mechanism was clarified by scanning electron microscopy, electron probe micro-analysis, and transmission electron microscopy. After the three-point bending test, interfacial debonding was observed predominantly at the incoherent W-TiN rather than at the semi-coherent Ta-TiN interfaces. At 0.30 GW/m2 of electron beam thermal shock, the average width and depth of thermal shock cracks in the W/Ta laminated composite were - 9.4 mu m and - 30.0 mu m, respectively, which were much smaller than those in the W/W laminates and W/TiN/Ta laminated composite.