NANOCRYSTALLINE NBAL3 POWDERS AND NBAL3 AL MULTILAYERS BY LASER-ABLATION DEPOSITION/

There is a considerable interest in nanocrystalline materials due to t heir unique atomic arrangements and the potential for novel properties (l). Nanocrystalline materials have the potential to realize novel pr operties, such as improved ductility of ceramic materials like TiO2, s ome of which have already been observed by various researchers. Enhanc ed solid solubility, specific heat, thermal expansion, and low tempera ture ductility of ceramics are other examples of novel or enhanced pro perties. One of the important challenges in synthesizing and studying nanocrystalline materials is the low yield, on the order of 0.1-0.3 gm /hr (2,3), for the present gas condensation technique. Several alterna tive methods, including laser ablation (4-6), sputtering (7), Sol-gel (8), high energy ball milling (9), and hydrothermal pyrolysis (10), ar e presently being explored by various researchers. This paper describe s a comprehensive approach to study laser ablation process for synthes is of nanocrystalline intermetallic powders and multilayers by using: on-line absorption spectroscopy for characterization of ablation plume and powder yield; electron microscopy for microstructure evaluation a nd EDS for composition. (C) 1997 Acta Metallurgica Inc.