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Comparison of Elastic and Anelastic Properties of SiC and MoSi2/Ti5Si3 as a Function of Temperature
註釋The piezoelectric ultrasonic composite oscillator technique (PUCOT) was used at frequencies near 120 kHz to measure the elastic and anelastic properties of two kinds of advanced ceramics as a function of temperature (T) up to about 1300 K and of strain amplitude in the range 10-7 to 10-4. The specimens consisted of commercially available silicon carbide (SiC) from Norton Co., reaction-formed SiC (RFSC) [with and without molybdenum disilicide (MoSi2) additions] made at NASA Lewis Research Center, and MoSi2/Ti5Si3 [With Ti5Si3 (pentatitanium trisilicide) concentrations in the range 10 to 50%] made at Los Alamos National Laboratory. The measured values of dynamic Young's modulus, E, damping, Q-1 and strain amplitude were analyzed. The main findings are: The Values of (1/E(0))(dE/dT), where E(0) is the value of E at room temperature, fall near -3 X 10-4 K-1; the damping in the materials is small and independent of strain amplitude for most of the specimens and temperatures used; and limited data for the silicides with 30 and 40% Ti5Si3 indicate a breakaway of the strain amplitude dependence of damping. The similarities and differences in the behavior of the mechanical properties are discussed for the two types of material.