CHARACTERISTICS OF AMORPHOUS MN3ALC PHASES FORMED BY MECHANICAL MILLING

Amorphization of Mn carbides by rapid quenching method has been proved to be unsuccessful. By mechanical milling in the present work, amorph ous phases have been formed in the perovskite-type Mn(3)AIC compound. The transformation process from crystalline to amorphous phase was fou nd to be milling time controlled, and 10 h is a critical period for th e macroscopically single amorphous phase to form. It has been clarifie d that the redistribution of C atoms is an instinctive factor for amor phous phase to nucleate, and the atomic configuration in the amorphous phase is changed much in longer milling that different crystallizing behaviours have been caused. With X-ray diffraction and differential s canning calorimetry (DSC) results, an atomic configuration transition model is considered for the structures of the amorphous phases changed during milling.