Nanostructure by design: Solution-phase-processing routes to nanocrystalline metals, ceramics, intermetallics, and composites

Solution-phase processing affords nanoparticles and nanocomposites of a wide range of materials, including metals, alloys, intermetallics, and ceramics, with substantial control of particle size, particle morphology, microstructure, and composite microstructure. The particle size of nanocrystalline Cu (nano-Cu) produced by the reduction of CuCl can be varied between 10-30 nm by changes in reducing agent and solvent, while that of nano-Al can be varied between 45-180 nm. The morphology of nano-AlN produced by nitridation of nano-Al can be varied from almost entirely equiaxed to almost entirely whisker-like. Nanocrystalline nickel aluminides can be synthesized by reacting NiCl2 and LiAlH4 in organic solvents, followed by solid-state heating. When the reaction is performed in aromatic solvents the desired phase is obtained vith a porous, highly sintered microstructure, while reactions performed in ethereal solvents yield nonsintered nickel aluminide particles in an amorphous alumina matrix. Nanocrystalline composites of AlN and Al are prepared by suspending the AlN particles in organic solvent, and performing solution-phase chemistry to produce nano-Al. (C) 1998 Elsevier Science Ltd. All rights reserved.