Characterization of the damping properties of die-cast zinc-aluminum alloys

Characterization of the mechanical damping properties of a series of die-cast zinc-aluminum alloys is described. Over the range of variables (temperature, frequency, and vibration strain amplitude) normally encountered in service applications, it is shown that the damping consists of two components. Both components are due to linear relaxation mechanisms: the first is a thermoelastic relaxation and the second is the low-temperature tail of a broadened boundary relaxation. Some of the alloys exhibit elevated damping levels over a useful frequency range, particularly at the temperatures encountered in under-hood applications in automobiles. This paper is based on a presentation made in the symposium “Acoustic/Vibration Damping Materials” presented during the TMS Fall Meeting, Indianapolis, IN, October 1–5, 1989, under the auspices of the TMS Physical Metallurgy Committee.