Ultrasonic testing of extruded and rolled green compacts from TiAl

This paper reports the correlation between the microstructure of extruded elemental powder semi-finished products from TiAl and the ultrasonic (UT) attenuation and ultrasonic velocity. For these investigations a newly developed ultrasonic measurement system was used, which allows the utilization of commercial pulser/receiver device. The complete digitization of UT A-scans as well as their processing is realised by means of a PC. The software developed for these investigations makes possible a semi-automatic data processing. The UT attenuation results from peak amplitudes measurement of successive back wall echoes, and titanium agglomerates could be found. The UT velocity is determined from cross-correlation of two successive back wall echoes and delivers in comparison to the peak value, and/or threshold method, more exact results. (C) 1997 Elsevier Science Ltd. All rights reserved.