Materials Characterization at High Temperatures Using Laser Ultrasound

A new technique is presented allowing measurement of ultrasonic absorption up to very high temperatures in polycrystalline and other materials exhibiting strong scattering, by generating reverberation fields by short laser pulses, and by observing their decay using optical interferometers for detection. Furthermore, the elastic constants in the material examined can be evaluated by measuring the time-of-flight of the ultrasonic pulses. Ultrasonic absorption data and elastic constants in aluminum, SiC ceramics, and white cast iron are presented as a function of temperature up to 1400K.