MICROSTRUCTURE AND HARDENING OF AL-BASED NANOPHASE COMPOSITES

Part amorphous-part crystalline Al-Ni-Y alloys can be produced by devi trification of melt-spun fully amorphous alloys. These materials have a novel structure of nanometre-sized crystals of sigma-Al in an amorph ous matrix and can be regarded as nanophase composites. Devitrified mi crostructures are studied by X-ray diffraction and transmission electr on microscopy. The significant hardening accompanying devitrification is characterised for various heat treatments, and is mainly attributed to the solute enrichment of the remaining amorphous phase. The harden ing kinetics are, however, also influenced by the composition uniformi ty of amorphous matrix. (C) 1997 Elsevier Science S.A.