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Net-shape and crack-free production of Nd–Fe–B magnets by hot deformation

2013; Elsevier BV; Volume: 589; Linguagem: Inglês

10.1016/j.jallcom.2013.11.188

1873-4669

Imants Dirba, Simon Sawatzki, Oliver Gutfleisch,

Magnetic Properties and Applications

In order to reduce the amount of material waste and therefore to use the precious rare earth element Nd in a more efficient way, routes for the production of crack-free hot-deformed nanocrystalline Nd–Fe–B magnets (using melt-spun ribbons as a precursor) have been investigated. In contrast to the conventional route in which material flows into a cavity, pressing tool has been used in order to exert a back pressure during backward extrusion, leading to crack-free and net-shape production of radially oriented ring magnets, without detrimental influence on magnetic properties. Micrographs demonstrate overall good alignment of elongated platelet shaped grains with radially oriented c-axis in most parts of the ring. A mean remanence Jr = 1.27 T and coercivity μ0iHc = 1.5 T has been obtained. Degree of texture reaches around 0.7. Furthermore, die-upsetting has been performed for different degrees of deformation to obtain crack-free, mechanically and magnetically homogenous, axially oriented tablet magnets.