PHASE STABILITY IN Al/Ti MULTILAYERS

摘要

Structural stabilities in thin-film Al/Ti multilayers have been studied using transmission electron microscopy. It is shown that models based on interface-induced modifications to bulk stacking fault ener- gies, and/or coherency-strain energy may not be used to explain the various phase transitions observed. Rather, phase stability may be rationalized by reference to a new model based on classical thermodyn- amics. involving the competition between bulk and interfacial energies. Thus, these phase transitions are shown to be driven by reductions in the overall interfacial energies. A biphase diagram (reciprocal of bilayer thickness vs composition) has been developed for the multilayers produced by magnetron sputter- ing. The influence of impurities possibly introduced during thin-foil preparation is considered and rational- ized by reference to the biphase diagram for this system.