Metastable phases in vapour‐quenched Al 78 Cu 22 film

The structure and structural changes of an Al 78 Cu 22 (at%) alloy film produced by coevaporation onto a cooled substrate have been investigated with transmission electron microscopy. A series of metastable phase transitions were observed during the crystallization from the as‐deposited amorphous phase to the final equilibrium state. The deposit structure at room temperature consists of a mixture of fine grained α' crystallites (fcc, α = 4.81 Å) with an amorphous phase, and some welldefined crystals with an fcc lattice ( a = 7.18 Å, namely α 1 ). The subsequent annealing led to the grown crystals transforming to an ordered α′ phase. It is argued that the development of such a transition is the result of a gradual atomic rearrangement – first topologically then a chemically predominant disorder‐order transition.