FAR-FROM-EQUILIBRIUM PHASE-TRANSITION INDUCED BY MECHANICAL ALLOYING IN THE CU-FE SYSTEM

By means of X-ray diffraction patterns, scanning electron microscopy observations, chemical energy-dispersive analyses and thermal stability studies (differential scanning calorimetry and thermomagnetometry), the far-from-equilibrium phase transition induced by mechanical alloying in the Fe-Cu system has been investigated. On the Cu-rich side of the phase diagram a supersaturated f.c.c. crystalline (Cu) solid solution is detected, while on the Fe-rich side a supersaturated b.c.c. (Fe) solid solution is detected. The sticking of the Cu particles which occurs during milling (leading to a Cu end-product depletion) is avoided by the addition of an ethanol fluid to the initial Fe and Cu powder mixture, resulting in a better homogenization of the end-product (in terms of composition). In this case an amorphous phase has been found in addition to the former supersaturated crystalline phases.