KINETICS OF PHASE-CHANGE IN EXPLOSIVELY SHOCK-TREATED ALUMINA

The effect of shock treatment on the kinetics of transformation of transition‐phase alumina has been examined. Alumina powder, consisting of spherical particles produced by melting and quenching, was shock‐treated at 13‐ to 26‐GPa maximum pressure and subsequently heat‐treated at 1000° and 1050°C for various times. At 1050°C, the transformation of unshocked powder was typical of other aluminas with an incubation period of 60 min before significant conversion occurred. In contrast, in the shock‐treated material, no incubation period was observed and the α‐phase content increased exponentially with time. The growth kinetics of the shocked powder corresponded to a linear growth process with an activation energy of 482 kJ/mol. TEM examination revealed α‐phase morphologies consistent with linear growth. Copyright © 1990, Wiley Blackwell. All rights reserved