Experimental study of Young’s modulus and internal friction of low-melting-point gallium using modified piezoelectric ultrasonic composite oscillator technique

As an emerging multifunctional metal with the lowest melting point except for mercury, gallium combines a wide range of metallic and non-metallic elements to form advanced semiconductors critically important in cutting-edge technologies. However, due to its low melting point and poor machinability, it is quite difficult to simultaneously characterize gallium’s elastic properties and damping characteristics using conventional methods, which is essential in designing and evaluating gallium-based structures. Therefore, developing effective methods to achieve accurate and efficient measurements of Young’s modulus and corresponding internal friction of gallium is of great significance. This letter studies simultaneous measurements of the variations in Young’s modulus and internal friction of gallium at varying temperatures by employing the modified piezoelectric ultrasonic composite oscillator technique. Combining the explicit theoretical formulas with the measured resonance and anti-resonance frequencies, it has been discovered that Young’s modulus undergoes an approximately linear decrease as the temperature rises, declining from 83.84 GPa at -70 °C to 79.37 GPa at 20 °C. Moreover, like aluminum in the same Group ⅢA of the Periodic Table of Elements and exhibits a grain-boundary internal friction peak, gallium displays a longitudinal internal friction peak at approximately -12 °C, with the peak value reaching 1.77 × 10−3. This basic research on gallium’s elastic properties and damping characteristics under low-temperature conditions will inspire further explorations of the mechanical properties of a diverse spectrum of low-melting-point functional materials and facilitate applications of gallium-based structures under complex conditions.