SGER: Magnetically-Triggered Joining Using Nanocrystalline Fe-Al Powders

Dartmouth College, Hanover NH

Investigators

Abstract

Joining materials, particularly dissimilar materials, effectively and inexpensively while not degrading their properties is of great practical value. The research objective of this award is to evaluate a proposed new method for joining. The method involves using an alternating magnetic field (AMF) to generate hysteresis losses in two-phase nanocrystalline powders in which one of the phases is ferromagnetic and the other is aluminum. When the powders are subjected to an AMF of appropriate strength and frequency, the ferromagnetic phase heats up, triggering an exothermic reaction between the phases. The heat output from this magnetically-triggered reaction can be used to either melt the powders to form a joint directly, heat a joining layer of solder or braze, or melt the surfaces of the materials to be joined. The metal aluminide resulting from the reaction will solidify into a new non-ferromagnetic crystal structure, which cannot be subsequently heated by an AMF. The research effort will be to produce powders, characterize them both microstructurally and magnetically, and examine joining different materials under an applied AMF. The method is generic and could, in principle, be applied to many materials and used for many applications.