Determination of elastic constants in materials submitted to high temperatures with an ultrasonic method

An ultrasonic device has been developed to measure the shear and compression waves velocities up to 1000 degrees C on cylindrical specimens. A contact impulse method is used, with wave-guides to protect the ultrasonic transducer from the thermal exposure. The measurement of time-of-flight in the specimen is performed on different paths corresponding to transmissions and reflections which allows to exclude the effects of temperature gradients in wave-guides. Data processing is adjusted to take into account various deformations undergone by the time profile of the echoes (especially phase rotation and frequency scattering). This device was used for metallic and composite material. The accuracy on the elastic constants is in the order of 1 %.