CHARACTERIZATION OF ALNI FORMED BY A SELF-SUSTAINING REACTION DURING MECHANICAL ALLOYING

We report on electron-microscopic studies of AlNi powder formed by an explosive reaction during mechanical alloying. In situ thermal analysis enabled us to terminate the milling process immediately following the reaction, so that further mechanical damage to the reaction product was minimized. The surfaces of the resulting particles are smooth on a scale of tens of nanometers. We suggest that explosive reactions occur in individual grains during mechanical alloying even for seemingly gradual reactions, and that amorphous phase formation could involve such mechanism.