Mechanistic Aspects of Mechanically Induced Phase Transformations
F. Delogu1, G. Mulas2, S. Enzo2, L. Schiffini2 and G. Cocco2
1Dipartimento di Ingegneria Chimica e Materiali, University degli Studi di Cagliari,
Piazza d'Armi, I-09123 Cagliari (Italy)
E-mail: delogu@dicm.unica.it
2Dipartimento di Chimica, University degli Studi di Sassari,
Via Vienna 2, I-07100 Sassari (Italy)
Страницы: 157-162
Аннотация
In the field of mechanochemistry, the exact nature of the atomistic processes underlying physical and chemical transformations under mechanical processing conditions is a long-standing problem. Far from being satisfactorily solved, the lively debate associated has constantly stimulated the development of conceptual frameworks alternative to the defect-enhanced thermal diffusion scenarios initially proposed. Different approaches laying emphasis on the capability of mechanical forces to induce atomic scale mixing phenomena independent of thermal contribution were thus investigated. Along this line of inquiry, molecular dynamics simulations were here employed to gain deeper insight into the atomic-scale processes induced at the phase boundary between crystalline Ni and Zr metal lattices by the application of a shear stress. The numerical findings show that the application of shear stresses determines the deformation of the crystal and the formation of a sliding interface. Atoms with defective coordination appear at the interfacial region and gradually arrange into complex aggregates, the dynamics of which promotes the migration of atomic species and their gradual mixing near the interface. Chemical disordering processes take place at the interface, resulting in the formation of an amorphous domain.
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