Magnetically Graded Ni3Al Fabricated by Inhomogeneous Deformation and Heat Treatment

Abstract

The magnetic properties of Ni3Al intermetallic compound are influenced by the degree of order through the change of the number of Ni–Ni bonds at antiphase boundaries (APB). Since the degree of order can be changed by plastic deformation and heat treatment, the fabrication of magnetically graded smart materials based on Ni3Al intermetallic compound has been carried out by the following two methods: (1) an inhomogeneous compressive deformation using a wedge-shaped specimen and (2) an inhomogeneous heat treatment with temperature gradient. The magnetic properties are measured by the vibrating sample magnetometer (VSM) technique. It has been found that the magnetically graded smart materials with susceptibility gradient are successfully fabricated by either the compression deformation of the wedge-shaped Ni3Al or the inhomogeneous heat treatment. It has also been found that the degree of long-range order, S, varies depending on the position of the specimen. The susceptibility gradient is correlated with the gradient of the degree of long-range order S.