Correlation between elastic hysteresis caused attenuation of ultrasonic waves and the Q-factor in sintered Fe-Ni alloys

In binary alloys of Fe-Ni system, prepared by method of powder metallurgy, the ultrasonic absorption measurements have been done. The energy loss due to the mechanism of elastic hysteresis was separated from the total attenuation and the corresponding coefficients of absorption were determined. Finally, they were used to calculate the Q-factor of the materials. It was found that, in alloys with a single-phase FCC structure (over 30 % Ni), the Q-factor varies between 140 and 300 for longitudinal waves, and from 100 to 450 for shear waves. Otherwise, in the concentration range where the BCC-structure is present (10% to 30% Ni), the Q-factor reaches much higher values, up to 1905 for longitudinal waves and 893 for shear waves. For both types of ultrasonic waves, the composition dependence of the Q-factor exhibits well defined maximum for the alloy with the composition of 20 % Ni, which has a martensite structure and maximal value for Brinell hardness. (Original)