THE RETRO-EFFECT IN STOICHIOMETRIC CUAU - A RESISTOMETRIC STUDY

Long-range ordering and disordering in nearly stoichiometric CuAu (49. 4 at% Cu, 50.5 at% Au) has been investigated by dynamic in situ resist ometry. Linear cooling and linear heating, starting from constant init ial conditions, was performed at different rates of temperature change . For cooling runs the usual effect of undercooling was found, increas ing with increasing cooling rate. For heating runs, however, a shift o f the transformation temperature to lower temperatures with increasing heating rate was observed. This is similar to what has been previousl y reported for cyclic measurements (retro-effect). This effect is not influenced by isothermal annealing at 300 degrees C; it is probably co nnected with the nucleation stage of the phase transformation and ther eby with the microstructure of the material. (C) 1997 Elsevier Science Limited.