PHOTOACOUSTIC CHARACTERIZATION OF PHASE-TRANSITIONS IN AMORPHOUS METAL-ALLOYS

In this work a pulsed laser photoacoustic technique is employed in amo rphous alloys for the characterization of crystallization temperatures and the determination of the activation energies for the transitions. It is shown that the changes produced in the photoacoustic signal gen erated by low energy laser pulses (< 200 mu J), is a sensitive probe f or detecting the crystallization of a metallic amorphous sample. A pie zoelectric transducer attached to the sample by means of a glass subst rate was used for the acoustic detection. The developed technique has the advantages of requiring a minimum amount of sample, with no specia l sample preparation or conditioning. In order to demonstrate the vali dity of the technique, it was applied to the study of the crystallizat ion processes of the amorphous Mg-Zn alloy, comparing the result with respect to resistivity measurements.