ELASTIC-MODULI OF MOSI2-BASED MATERIALS

We prepared MoSi2, two-phase MoSi2/Mo5Si3, and (Mo, W)Si2 solid-solution alloy powders by mechanically alloying mixtures of elemental molybdenum, silicon, and tungsten. These powders were consolidated by hot-pressing them at 1500-degrees-C in graphite dies. We measured the elastic moduli of these alloys by a recently developed technique for non-contact ultrasonic spectroscopy. Second-phase Mo5Si3 additions to MoSi2 result in decreased values for G and E, whereas alloying MoSi2 with WSi2 results in increased values for G and E. An analysis of these Young's moduli and of data from the literature for various intermetallic alloys suggests that for any given alloy system, the Young's moduli for its various intermetallics as a function of density fall on a straight line. Further, the lines for the different alloy systems are approximately parallel.