Elastic properties of a boron-aluminum composite at low temperatures

Elastic properties of a boron-filament-reinforced aluminum-matrix composite were studied experimentally. Assuming transverse-isotropic elastic symmetry, five independent elastic constants were measured using a piezoelectric composite-oscillator method. Two constants, Young’s modulus along the filament axis and the torsional modulus perpendicular to the filament axis, were determined between 300 and 4 K. The composite’s elastic-constant values are between the values of boron and aluminum, but closer to that of aluminum. Along the filament axis, Young’s modulus is 2.30×1011 N/m2. Cooling from 300 to 4 K increases all the elastic stiffnesses by as much as 11%.