Experimental Investigation of Galfenol Elastic Properties and Auxetic Behavior

Iron-gallium alloys (known as Galfenol) are one of only a few metal alloys known to exhibit large auxetic or negative Poisson’s ratio behavior. The mechanical properties of Galfenol, including the auxeticity, are strongly dependent on the composition of the alloy. This research seeks to measure the elastic properties of Galfenol through a range of practical compositions in order to create a database as well as present trends in the elastic properties. This is achieved through tensile testing of single-crystal Galfenol dog-bone-shaped specimens and through Resonant Ultrasound Spectroscopy (RUS) of small parallelepiped samples. The effects of heat treatment were also studied. This project will enable future researchers to refer to the elastic properties of the alloy measured using two different techniques, as well as enable them to select the alloy with optimum elastic properties for their applications.