[Isothermal ordering processes of equiatomic alloy CuPt (author's transl)]

Isothermal ordering processes of equiatomic alloy CuPt quenched from above the critical temperature were investigated by means of electrical resistivity measurements, X-ray diffraction and electron microscopic observations. The main results obtained are as follows; (1) two different orderings are recognized at above and below 560 degrees C. Each main reaction is an ordering process having the activation energies of 30.6 and 17.4 kcal/mol, respectively. (2) In the early stage of ordering at the temperature below 200 degrees C the growth of disperse order is recognized by the increment of electrical resistivity, and has an activation energy of 30.1 kcal/mol. (3) At the temperature between 300 degrees C and 560 degrees C, the process of ordering consists of three stages having an activation energy of 17.4, 23.6 and 65.3 kcal/mol, respectively. These correspond to the ordering processes by the migration and the annihilation of quenched-in excess vacancies, the annihilation of secondary defects and the diffusion of equilibrium vacancies, respectively. (4) At the temperature above 560 degrees C, the process of ordering consists of two stages. The bulk of the ordering is a homogenous ordering within the grain.