Shock Compaction of an Acicular Iron-Alloy Powder to Produce a Nanocrystalline Magnet

Publisher Website
Google Scholar
Abstract
A shock-compaction technique of an acicular magnetic iron-alloy powder was developed to produce a nanocrystalline magnet preserving its magnetic properties and acicular features. Although a precompacted disk of the powder had undesirable initial conditions which were a large porosity of 50% and a wide distribution of pore size, use of a double-plate flyer consisting of copper and aluminum made it possible to produce a good compact having a density 98% of the theoretical value, 6.2 GPa Vicker's microhardness, and maximum energy product of 15.1 kJ/m3. One-dimensional wave-propagation analysis implies effective compression at the initial stage suppressing the total thermal energy and the localization of heat in the vicinity of large pores. The method is discussed for improving the magnetic properties.