Acceleration of mutual diffusion of niobium and tantalum during thermal cycling

It is shown, that in the process of thermal cycling of tantalum-niobium bimetal in the temperature ranges 1685-1715 and 1600-1800 deg C relative change in mutual diffusion coefficient averaged in time is within measurement error, i.e. it does not exceed 20-30%. On the contrary, in the process of thermal cycling in the temperature range 900-1450 deg C mutual diffusion coefficient increased by a factor of 2.5-6, as compared with prolonged isothermal annealing. The observed effect is related to the diffusion acceleration during metal plastic strain, which has been described in literature. The method of mutual diffusion coefficient comparison in thermocycled and isothermally annealed samples is discussed