The pressure dependence of the diffusivity of transition elements (tables 15 to 19) was studied by using the radio-tracer method, with serial sectioning by microtome. The radio-isotopes were implanted so as to avoid problems with oxide hold-up and with the low solubility of transition elements. Diffusion annealing was then carried out in a high-pressure cell at Ar pressures of up to 0.8GPa. The activation volumes for diffusion were determined by isothermal annealing. It was recalled that the activation volumes of non-transition elements were close to one atomic volume, and were not very different from the activation volume for self-diffusion. On the other hand, the transition elements had diffusion activation volumes of between 2.7 and 1.67 atomic volumes. They were also characterized by high activation enthalpies and pre-exponential factors. The results were explained in terms of differences, in vacancy-solute interaction, between transition and non-transition solutes.

G.Rummel, T.Zumkley, M.Eggersmann, K.Freitag, H.Mehrer: Zeitschrift für Metallkunde, 1995, 86[2], 131-40

Table 15

Diffusivity of 54Mn in Al at 925.2K

under Hydrostatic Pressure

Table 16

Diffusivity of 59Fe in Al under Hydrostatic Pressure

Table 17

Diffusivity of 57Co in Al under Hydrostatic Pressure

Table 18

Diffusivity of 51Cr in Al at 927K

under Hydrostatic Pressure

Table 19

Activation Parameters for the Diffusion of Various Elements in Al