ON THE ELASTIC MISMATCH IN THE ORDER-DISORDER TRANSFORMATION AND SOLID-STATE AMORPHIZATION OF INTERMETALLIC COMPOUNDS .2. CRITERIA FOR THE SOLID AMORPHOUS TRANSFORMATION IN INTERMETALLIC COMPOUNDS

Using simple thermodynamic considerations for the Gibbs-free energies of the crystalline and amorphous states a general condition for the solid-state amorphization of intermetallic compounds by irradiation or mechanical impact was derived. It was obtained that the amorphization is possible if the maximum elastic energy, DELTA-H(el)m, stored during the (chemical) order-disorder transition is larger than DELTA-H(top)a, the enthalpy of the topological change of amorphization. This condition can be rewritten into the form; the amorphization is not possible if the order-disorder temperature is less than the melting temperature. T(c) < T(m), and if T(c) > T(m) - in contrast to Johnson's condition - the possibility of the amorphization depends on the relative magnitude of the elastic mismatch energy and the chemical energy of ordering. If their ratio is large enough the amorphization is possible. Detailed calculations, carried out for a large number of compounds, led to a satisfactory agreement with the experimental observations.