Ultrasonic investigation of materials—An avenue for project-based learning

Project-based learning (PBL) provides an effective practical application to the learners. Further, PBL develops problem-solving, critical thinking, etc., in the learner. This paper describes a type of project offered to the students at the collegiate level to enhance the students' ability to work in a team, manage a project, and present their results. These projects use acoustic waves in the ultrasound frequency range that can be used as a powerful nondestructive tool for the characterization of the materials. In situ measurement of the ultrasonic longitudinal velocity and evaluation of the elastic constants carried out on the materials in solid pellet form over a wide range of temperatures at a fundamental frequency of 5 MHz enables the study of various phase transitions, such as metal to insulator, ferromagnetic to paramagnetic, and even structural phase transitions that occur in the materials. Here, the investigation is elaborated on using ultrasonic waves on some materials in pellet form and the results obtained are presented.