Charge transfer induced critical deformation in ion beam amorphized metallic alloys

Crystalline, or amorphous phase nucleation in binary metallic alloys ion bo mbarded under conditions suitable to form dense collision cascades, depends both on non-equilibrium and on thermodynamic mechanisms. In the Segregatio n Charge Transfer (SCT) model, at the spike-matrix interface, relaxation to (meta)stable equilibrium is simulated by a Charge Transfer Reaction (CTR) involving a couple of dissimilar atoms of the starting alloy: as a result a couple of singly ionized atoms, representative of an effective alloy is fo rmed. Structural stability is studied, comparing the volume of the CTR prod ucts to the volume occupied in the starting alloy by the corresponding pare nt atoms. The absolute value of the volume change induced by a CTR is evalu ated and related to the local lattice deformation induced by the same CTR. Destabilization of the starting alloy lattice occurs at a threshold deforma tion value: volume changes lie above the threshold in amorphized alloys and below it in crystallized alloys. (C) 1999 Elsevier Science B.V. All rights reserved.