Computer simulations of disordering and amorphization kinetics in intermetallic compounds
Molecular dynamics computer simulations on three intermetallic compounds, Cu,Au, Ni,AI and NiAl, have been performed to investigate the kinetics of the disordering and amorphization processes. These systems were chosen because reliable embedded atom potentials were developed for the constituent species and their alloys, and also because extended experimental results are available for them. Previous simulations of collision cascades with 5 keV Cu and Ni primary knock-out atom (PKA) showed a significant difference between the evolution of the short range order (SRO) and the crystalline order (GO) parameters in all of the intermetallics: a complete loss of the crystalline structure and only partial chemical disorder in the core of the cascade [T. Diaz de la Rubia et al., Phys. Rev. B 47 (1993) 11483; M. Spaczer et al., Phys. Rev. B 50 (1994) 13204]. The present paper deals with the simulation of the amorphization process in NiAl by 5 and 15 keV Ni PKAs. The kinetic energy of the atoms in the simulated systems was removed on different time scales to mimic strong or weak coupling between electrons and phonons. No evidence of amorphization was found at the end of the cascades created by the 5 keV recoils. However, the 15 keV PKA events showed that (i) in the no-coupling case the system evolved to a highly disordered state, (ii) an amorphous region with about 100 non-lattice atoms was found in the case of weak coupling, (iii) the locally melted and recrystallized region collapsed to a small dislocation loop when medium coupling was used and (iv) a highly ordered state resulted in the case of strong coupling.
2nd International Conference on Computer Simulation of Radiation Effects in Solids, JUL 24-29, 1994, SANTA BARBARA, CA
Record created on 2008-04-16, modified on 2016-08-08