Ultrasonic In-Situ Monitoring of Aluminum Alloy During Solidification and Melting

Abstract

In both research and production involving solidification of materials, it would be beneficial to have an in-situ, real-time characterization of the material properties during solidification process. In this work ultrasonic in-situ monitoring of aluminum alloy (Al-12.6%Si) during solidification and melting using a high temperature ultrasonic sensor is presented. The ultrasonic sensor used mainly consists of a conventional piezoelectric transducer, a titanium buffer rod as an acoustic waveguide and a cooling system. A steel reflector is assembled at the probing end of the sensor to make time-of-flight measurements. The sustainability of the sensor has been evaluated for long time immersion up to 16 hours in the molten aluminum alloy and the possible reaction at the outer wall of the titanium rod has been examined. It has been demonstrated that the titanium buffer rod has good wettability and sustainability to molten aluminum. Using the ultrasonic sensor, pulse echo measurements with the aluminum alloy have been performed in temperature range from 200 to 800 °C. The changes of the longitudinal velocity of the aluminum alloy during solidification and melting processes have been successfully monitored. In addition the change in the amplitude of reflected echoes during solidification is discussed.