BALL MILLING OF SYSTEMS WITH POSITIVE HEAT OF MIXING: EFFECT OF TEMPERATURE IN Ag-Cu
1997; Elsevier BV; Volume: 45; Issue: 7 Linguagem: Inglês
10.1016/s1359-6454(96)00388-6
ISSN1873-2453
AutoresThomas Klassen, U. Herr, R. S. Averback,
Tópico(s)Metallurgical and Alloy Processes
ResumoAg50Cu50 alloys prepared by ball milling were subsequently milled at different temperatures ranging from about 85 to 473 K and investigated by X-ray diffraction and differential scanning calorimetry. Milling at subambient temperatures led to a homogeneous f.c.c. solid solution, while milling at 473 K led to a fully decomposed, two-phase mixture. Partially decomposed systems were obtained during milling at intermediate temperatures with three co-existing phases all present. The milling-induced decomposition process had a very low apparent activation enthalpy, ≈ 0.11 eV, which is attributed to a first-order kinetic process involving non-equilibrium vacancies. The results are discussed in terms of competing mixing and de-mixing reaction rates.
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