Experimental investigation of the dynamic elastic modulus and vibration damping in MoSi2-30%Si3N4 as a function of temperature

The dynamic elastic modulus, E, and vibration damping of molybdenum disilicide (MoSi₂) with 30% volume addition of silicon nitride (Si₃N₄) were measured at varying temperatures using the piezoelectric ultrasonic composite oscillator technique (PUCOT). The value of the elastic modulus of the composite was observed to decrease as temperature, T, was increased. The value of dE/dT of MoSi₂ was determined to be −0.03 GPa/K. The vibration damping of MoSi₂-30%Si₃N₄ increased as temperature was increased, with an effective activation energy of 0.076 eV/atom. This was an average over the entire temperature range, but two distinct slopes were observed in the plot of damping versus inverse temperature.