Formation of metastable phases during heat treatment of multilayers in theAl-Pt system

This communication reports that several metastable phases form subsequently during heat treatment (up to 500 degreesC) of Al-rich Al-Pt multilayers. B esides the known a(amorphous)-Al2Pt, formation of two metastable phases wit h a composition close to Al5Pt was also observed in a transmission electron microscope. One of them corresponds to a phase given by space group P4 in Pearson's collection of intermetallic compounds. The other, a hexagonal pha se (a=12.4 Angstrom and c=26.2 Angstrom) is the one that was observed in ra pidly solidified Al-Pt alloys [L. Ma, R. Wang, and K. H. Kuo, J. Less-Commo n Met. 163, 37 (1990)]. Formation of these phases under different condition s is reported here. (C) 2001 American Institute of Physics.