Tensile properties of binary and alloyed Galfenol

Iron–gallium alloys, known as Galfenol, have a unique combination of magneto-mechanical and structural properties that make them an attractive choice for use in robust sensing, actuating, and energy harvesting devices. The high strength and toughness of Galfenol, when compared to traditional active materials such as Terfenol-D and piezoelectric ceramics, are leading to multi-functional (structural and active) applications, such as active-damping engine mounts. Although the toughness of Galfenol is high compared to other functional materials, further improvements in toughness and ductility are beneficial for structural applications. Qualitative analysis of fracture surfaces from binary Galfenol tensile specimens suggests an inverse correlation between the degree of intergranular fracture and the amount of plastic deformation. This implies that modifications to the alloy composition or processing that change the fracture mode from intergranular to transgranular could increase the ductility of the alloy. This paper examines the effect of small additions of tertiary alloying elements (C, Cr, Al) and mixing with low carbon steel (with and without V additions) on the tensile properties and fracture mode of Galfenol. Generally, the addition of alloying elements increased both strength and ductility and changed the fracture mode from intergranular to transgranular fracture.