Main trends in mass transfer of nickel in iron and copper under pulse effect

The main features of the phenomenon of mass transfer of radioactive Ni-63 in iron and copper under a pulse effect (i.e, under an externally applied impulse pressure) for energies ranging from 0,1 to 2000 J/cm(2) are investigated. The duration of ail impact was changed from 10(-6) to 0.1 s. The analysis of experimental data showed that the concentration profile after mass transfer is given by the equation: C= C(o)exp(-alphax(n)). In the case of diffusion at constant temperature and without an external effect, a power n = 2 is expected. Under impulse treatment n decreases and ranges from 0.8 up to 1.8. The investigations show that an increase of the energy E of the impulse results in a corresponding increase of the energy applied to the atoms which move in the lattice. This additional energy is expressed by the form of a driving force implying a directional motion of the atoms. According to the magnitude of this additional driving force, the atomic movement mechanism can be changed. It is reflected in a correlative change of power n with increasing energy of the impulse. If n is in the order of 2, the random-jumps' mechanism dominates; n approximate to 1 corresponds to a flux of atoms in conditions of high-energy effects (E similar to 1000 J). In this case, a mechanism of interstitial movement becomes a possible candidate for explaining the observed apparent diffusivity. When ranging between I and 2, the power characterizes an intermediate case, when diffusion occurs by several mechanisms simultaneously.