Measuring elastic constants of laminated Copper/Niobium composites using resonant ultrasound spectroscopy

Abstract

Layered copper/niobium (Cu/Nb) composites with small layer widths contain a high area per unit volume of solid-state interfaces. Interfaces have their own elasticity tensor, which affects the elastic properties of the composite as a whole. We have studied the elastic constants of Cu/Nb composites with different layer thicknesses with a view to determining the elastic constants of Cu/Nb interfaces. Our work relied on resonant ultrasound spectroscopy (RUS): a technique for deducing elastic constants from measured resonance frequencies. Resonance frequencies of three samples with differing layer widths were measured. A numerical approach for matching measured and computed resonance frequencies was developed and used in deducing the elastic constants of the composite. The uncertainties in the elastic constants thereby obtained were too large to estimate interface elastic properties. However, several sources of this uncertainty were identified, paving the way to improved elastic constant measurements in the future.