Effect of Carbon and Boron on Diffusivity of Deuterium in Molybdenum and Tungsten

The desorption behavior of deuterium from molybdenum, Mo-0.001 mass %C, Mo-0.06-0.092 mass %B, tungsten and W-0.011 mass %C prepared with arc-melting in Ar-10%D₂ was studied using a vacuum desorption method in the temperature range of 533–1152K. The diffusivity of deuterium measured for molybdenum was D=4.97x10⁻⁷ exp(−36.7kJ/mol/RT)m²s⁻¹ and D=1.77x10⁻⁶ exp(−55.8kJ/mol/RT)m²s⁻¹ for tungsten. The diffusivity of deuterium for both molybdenum and tungsten decreased with an addition of C and B. This decrease was considered due to the trap effect of carbide and boride. The trapping energy estimated was 54 kJ/mol for Mo-C and Mo-B and 82kJ/mol for W-C.