Simultaneous Synthesis and Consolidation of Nanostructured MoSi2

Abstract

A new process combining electric field activation and the imposition of pressure from mechanically activated powder mixtures is demonstrated as a means to simultaneously synthesize and densify nano-MoSi2 in one step. Nanophase reactants (Mo + 2Si) produced by mechanical activation are reacted by field activation with the simultaneous application of a uniaxial pressure. Mo + 2Si powders were comilled in a specially designed planetary mill to obtain nanometric reactants but to avoid formation of any product phases. These were then subjected to high alternating currents (1600 A) and pressures of 106 MPa. Under these conditions, a reaction is initiated and completed within a short period of time (3–6 min). The relative density of the product ranged from 82 to 93%. The crystallite size of the MoSi2 compound was determined by x-ray diffraction line-broadening analysis using the Langford method. The size ranged from 58 to 75 nm.