CRYSTALLIZATION BEHAVIOR OF AL85Y10NI5 BY ISOCHRONAL AND ISOTHERMAL ANNEALING

Crystallization of Al85Y10Ni5 by isochronal annealing showed a strong dependence on scan rate over the range of 0.9-20.7 K/min. At a scan rate of 0.9 K/min, crystallization of Al85Y10Ni5 occurred by primary crystallization in a single step. An increase in the scan rate from 0.9 to 1.99 and 4.3 K/min led to a three and five stage crystallization process respectively. A further increase in scan rate to 10.9 K/min and 20.7 K/min reduced the number of observed transformation steps. Resistivity measurements performed isochronally confirmed the complex crystallization sequence. Isothermal annealing revealed the presence of multiple phases in the devitrified glass by TEM/STEM with the predominant phase being a solid solution of Al, Y and Ni. The onset of a low temperature polymorphic phase transformation corresponding to a supersaturated solid solution (SS) phase in this alloy was not achievable.