Deformation behavior of polycrystalline Galfenol at elevated temperatures

Abstract

Magnetostrictive Galfenol (Fe-Ga) is a promising new active material. Single crystals of Galfenol have been shown to exhibit up to 400 ppm magnetostrictive strains with saturating fields of several hundred oersteds. Its robustness and ability to actuate in either tension or compression allows for new actuator and sensor designs. However, due to the high permeability of Galfenol, it needs to be in thin sheet form for many device applications to minimize eddy current losses. Work is underway to develop conventional rolling processes to produce large quantities of thin Galfenol sheet, while retaining a preferred <100> crystallographic texture to optimize magnetostrictive performance. Knowledge of deformation behavior at elevated temperature is crucial to understanding formability and crystallographic texture evolution during rolling. In this work, the high-temperature plasticity and the deformation behavior of polycrystalline Galfenol were investigated using conventional axial compression tests and rolling experiments. As the temperature increased, significant softening of the material occurred in the temperature range from about 450°C to 800°C. The results also suggested that significant dynamic recovery and recrystallization occurred during deformation at above 800°C.