Mechanical properties of tantalum-tungsten interlayer between tungsten tile and thimble to prevent helium leak from He-cooled divertor

Abstract

The tungsten parts made of pure tungsten tile and dispersion strengthened tungsten thimble with 3 mm interlayer of tantalum-tungsten alloy are fabricated by Spark Plasmas Sintering (SPS). The process of SPS is that the temperature is raised to 1700 °C at a rate of 100 °C/min and kept for 3 min, under a constant pressure of 50MPa along the Z-axis. The mechanical properties of the interlayer with different percent of tantalum are measured. The results show that with increasing percent of tantalum, the hardness first increases and then decreases; and as the indentation on the sample is closer to dispersion strengthened tungsten, the value of Vickers hardness is much higher. The Vickers hardness of interlayer is the highest when the content of tantalum is 50% and the indentation is next to dispersion strengthened tungsten. Bending strength drops with increasing content of tantalum, when the content of tantalum is 100% the value of bending strength is the lowest. The fracture toughness is highest as the content of tantalum is 25%, the value is 9.89MPa•m1/2. The toughening tungsten-tantalum interlayer between tungsten tile and thimble would better prevent helium leak from He-cooled divertor for DEMO.