Elastic Constants of a Tungsten-Particle Copper-Matrix Composite

抄録

Using a megahertz-frequency ultrasonic method, we measured the elastic constants of a composite consisting of seventy-volume-percent tungsten particles in a copper matrix. We report the Young, shear, and bulk moduli, and the Poisson ratio. Tungsten is much stiffer than copper: the Young-modulus ratio equals 410/129 = 3.2. Thus, from a linear rule-of-mixture, we expected large departures, which we found.(The Poisson ratio comes close to a linear rule-of-mixture.) Unexpectedly, we found a substantial elastic anisotropy: eighteen percent in the shear modulus. To model the system, we used a scattered-plane-wave ensemble-average approach. For the four elastic constants listed above, we found reasonable model-measurement agreement, one-to-seven percent for the averaged-over-direction measurements. Assuming oblate-spheroidal (c/a = 0.5) particles improves the agreement: two percent or less for the four cases.