Ultrasonic measurement of the temperature dependence of elastic moduli in light alloys

This paper presents a new method for evaluating the temperature dependency of ultrasonic shear and longitudinal wave velocities. Results of such measurements allow the determination of elastic properties of solids, such as Young's and shear moduli, for various temperatures. A short description of well-established techniques of ultrasonic measurements at high temperatures, such as laser and waveguide techniques, is given and their disadvantages listed. The main disadvantage, especially in the case of small samples with low heat capacity, is uneven temperature distribution in the sample volume caused by contact with a waveguide or through heat generated by the laser pulses. The proposed techniques enable velocity measurement of both longitudinal and shear waves in small samples while ensuring constant temperature in the whole sample volume. Measurements were performed using piezoelectric transducers pressed between two samples and generating and detecting ultrasonic waves propagating along the samples. Advantages of this measuring technique are: no need for couplant; the ability to measure small, easily machined samples; and the low cost of the experiment. The main disadvantage of the technique is a limited temperature range. The paper presents results of measurements performed on several samples cut from light alloy castings of various chemical compositions.