RADIATION-INDUCED CRYSTALLINE-TO-AMORPHOUS TRANSITION IN INTERMETALLIC COMPOUNDS OF THE CU-TI ALLOY SYSTEM

Recent progress in molecular-dynamics studies of radiation-induced crystalline-to-amorphous transition in the ordered intermetallic compounds of the Cu-Ti system is discussed. The effect of irradiation was simulated by the generation of Frenkel pairs, which resulted in both the formation of stable point defects and chemical disorder upon defect recombination. The thermodynamic, structural and mechanical responses of the compounds during irradiation were determined by monitoring changes in the system potential energy, volume expansion, pair-correlation function, diffraction patterns, and elastic constants. It was found that the intermetallics Cu4Ti3, CuTi and CuTi2 could be rendered amorphous by the creation of Frenkel pairs, but Cu4Ti could not, consistent with experimental observations during electron irradiation. However, the simulations showed that Cu4Ti did become amorphous when clusters of Frenkel pairs were introduced, indicating that this compound may be susceptible to amorphization by heavy-ion bombardment. A generalization of the Lindemann criterion was used to develop a thermodynamic description of solid-state amorphization as a disorder-induced melting process.