Interdiffusion in the Al-V System in the 800-1000 °C Temperature Range
摘要
Vanadium and its alloys have potential for application as fuel cladding in new fast breeder reactors cooled by sodium. Diffusion aluminide coatings could be a solution of choice in providing protection against high-temperature corrosion by liquid sodium or residual oxygen for these materials. In this work, multilayered coatings were formed on V and V-44Al substrates by halide activated pack cementation, using CrCl3 as transport agent and pure aluminum (high activity) as master alloy. Two types of diffusion couples, V/Al and V-44Al/Al, were investigated in order to determine the growth kinetics of the aluminide compounds in the 800-1000 °C temperature range. The growth of the saturated Vss as well as of the VAl3 and V5Al8 layers was controlled exclusively by solid state diffusion following a parabolic law, allowing the determination of the parabolic growth constants. Wagner’s analysis was adopted to calculate the integrated interdiffusion coefficients, resulting in values ranging approximately from 10−10 to 10−12 cm2/s for temperatures between 800 and 1000 °C. In general, VAl3 has the highest