First direct bulk synthesis of rare-earth-free hard magnet tetrataenite

>Despite many attempts with diverse approaches, bulk synthesis of tetrataenite has not been reported. Here it is shown that with appropriate alloy compositions, bulk synthesis of tetrataenite is possible, even in conventional casting at cooling rates 11‒15 orders of magnitude higher than in meteorites

Tetrataenite, an alloy of iron and nickel, is a hard magnetic material with a magnetic energy product comparable to neodymium iron boride, is stable at room temperature but not at high temperature and historically believed to only form through extremely slow (>10^6 years) crystal relaxation in iron-nickel meteorites. Nanopowder tetrataenite has previously been synthesized by various deposition, decomposition and milling processes, but these powders are not easily converted into macroscopic magnets, and generally produced in small amounts.

In this study, an intermetallic iron-nickel-phosphorus-carbon eutectic is shown to precipitate bulk tetrataenite as dendritic crystals upon annealing at industrially useful rates, demonstrating a potentially highly significant pathway for the production of permanent magnets from common materials.