Young's modulus and mechanical damping of silver dental alloys

The piezoelectric ultrasonic composite oscillator (PUCO) technique has been used at a frequency of 80 kHz to measure Young's modulus and mechanical damping in eight silver dental alloys. The time dependence for aging at 37° C and the temperature dependence of mechanical damping over the temperature range of 20 to 80° C were studied. Young's modulus (measured at 37° C) increased from around 17 GPa after 15 min and saturated near 70 GPa after 103 to 104min. The mechanical damping increased by factors of 6 to 32 over the investigated temperature range, whereas Young's modulus decreased by 1.3 to 5%. Arrhenius plots of the data gave effective activation energies ranging from 0.35 to 3.1 eV. The results are interpreted in terms of various diffusion processes in the alloys and in terms of the microstructures.