Processing and magnetostriction studies in binary iron alloys

In previous work it has been shown that the addition of gallium, a non-rare-earth element, to iron drastically increases magnetostriction by more than tenfold. This leads to the possibility that there are other non-rare-earth alloying elements that might also lead to large increases in the magnetostriction of iron. The phenomenon of magnetostriction is not well understood, so it is difficult to decide which elements when added to iron will lead to increases in its magnetostrictive properties. This dissertation examines the influences of alloying Fe with Group IVA elements and element Zn and is part of a larger systematic study of magnetostriction in binary alloys of Fe with non-rare-earth alloying elements designed to obtain a greater understanding of how alloying elements affect magnetostriction.; Group IVA alloying elements were selected because they are directly to the right of gallium on the periodic table, have the same total number (s + p) valence electrons but different atomic sizes, and have appreciable solubility in iron. Limited experiments performed on directionally grown samples of these alloys indicate that initially both Si and Ge increase the magnetostriction of Fe but decrease the magnetostriction at higher concentrations. Sn decreased the magnetostriction of Fe for all compositions examined. No direct correlation between the lattice parameter and magnetostriction was observed. Magnetostrictions observed were much less compared to those in Fe-Ga alloys, and this is attributed to the presence of the additional p electron in these solute atoms compared to Ga.; The second part of the study focused on binary Fe-Zn alloys. It is just to the left of gallium and so has a full d-shell and one less (s + p) electron in its ground state. Because of the previous results with the Group IVA elements, it was hoped that would increase the magnetostriction of iron nearly as much as gallium. The main difficulties with alloying zinc and iron are the disparities between the boiling point of zinc and the melting point of iron (∼600°C). A process for alloying zinc with iron by explosive compaction is outlined and some studies on diffusion processes that are important in creating these alloys are also put forward. Finally an explanation as to why zinc also gives low values of magnetostriction is attempted. Although zinc does not seem to hold much promise as a magnetostrictive addition to iron, the process used in alloying it and the groundwork laid for further exploration of iron-zinc alloys for further study is novel itself.