Grain Boundary Peak in a Foamed Zn—Al Eutectoid Alloy
摘要
We study experimentally the temperature spectra of internal friction (IF) and relative dynamic modulus (RDM) in a foamed Zn-Al eutectoid alloy.The specimens with macroscopic pores (0.5-1.0mm) were prepared in an air pressure infiltration process.The damping behaviour of the foamed Zn-Al eutectoid alloy is characterized by IF.The IF and RDM measurements at a maximum surface shear strain of 20×10^-6 have been made by using a multi-function internal friction apparatus at frequencies of 0.5,1.0 and 3.0Hz from room temperature to the equilibrium eutectoid isotherm of 277℃,while continuously changing the temperature cycle.At low frequency,an IF peak is observed in the IF temperature curve.The IF peak is of a grain boundary,which is associated with the diffusive flux on a crystalline boundary between the like-phases of Al/Al.Its activation energy has been calculated to be 1.10±0.06 eV and the pre-exponential factor τo is 10^-14 s in the IF measurements.