Computer modelling of isothermal annealing of cascade damage region in iron-alpha

The paper deals with the description of a model of short-time isothermal annealing in the region of damage created by a cascade of atomic collisions in alpha-iron. Using the 'HITANN' program which realizes this model, a study was made of the annealing process in characteristic cascade areas of the damage formed by the 1 to 15 keV recoil atoms. A monocrystal is considered in which the atoms occupy equilibrium positions in an infinite lattice of the respective type. The only imperfections of the lattice are point defects the initial positions of which are the basic data for modelling. Using the Monte-Carlo method the migration path of each defect is followed within a preset discrete sequence of time steps. The performed modelling of high temperature annealing comprises a time interval of 8.0x10-8 s at 3000 deg K and 2.9x10-8 s at 800 deg K. During this period of time a rapid transformation of short-time annealing of damages takes place. Hereby a part of defects gets annihilated. The mobile defects which have not been annihilated either join into low-mobile complexes in the area of initial damage, or escape from this area by way of diffusion. The modelling enabled to obtain average kinetic characteristics of the annealing process, the recombination and the complexing rates depending on the time, and also a spatial distribution of damages and distribution of complexes depending on the size after an installed time of annealing. The elements migration model is realized by the Monte-Carlo method. The annealing model algorithm is based on a cyclic repetition of a number of standard operations at each time step tau, therefore the increase in tau at the preset total time of annealing leads to a decrease in the computer time expenditure