Kinetic analysis of Al3Ti intermetallic powder after mechanical treatment in hydrogen

We present results of mechanochemical processing experiments performed on intermetallic powder, Al3Ti milled under hydrogen and helium atmospheres using a magnetically controlled Uniball device. Milling products were investigated by X-ray diffractometry (XRD), transmission electron microscopy (TEM) and advanced differential thermal analysis (DTA and DSC). Milling in both H2 and in He resulted in breakdown of the intermetallic structure and, after extended milling, formation of nanostructural products comprising, predominately, a solid solution of Ti in fcc Al, with some possible additional Al1+xTi1−x (x = 0.3) phase. Detailed kinetic analysis was preformed on the Al3Ti sample milled for 6 days in hydrogen. Under isothermal annealing, the crystallization of the Al5Ti2 was found to follow the JMA kinetics, with constant activation energy E∗ and Avrami exponent n decreasing from 2.5 to 1.5.