A GENERALIZED SOLIDIFICATION MODEL AND MICROSTRUCTURAL VERIFICATION FOR THE ND-FE-B-TI-C SYSTEM PROCESSED BY RAPID SOLIDIFICATION

For the Nd2Fe14B (2-14-1) compound, the optimal grain size should be s maller than the size of the single domain size of 150 nm. Transition m etal carbides (TMC) also reduce the quench rate necessary to achieve t he optimal or overquenched condition. This allows inert gas atomizatio n (IGA) to produce viable magnetic materials. In this article we will demonstrate that optimal microstructure for the 2-14-1 can be produced by IGA with the addition of TiC. Moreover, a solidification model wil l be presented to show (1) how recalescence is a critical feature to t he evolution of the microstructure in rapidly solidified materials and (2) the role TMC and other solute phases have on inhibiting grain gro wth so that lower quench rates can be employed. (C) 1997 American Inst itute of Physics.