Auger electron spectroscopy (AES) study on fractured rapidly-quenched and sintered NdFeB magnets

By using Auger electron spectroscopy (AES) to obtain chemical information from the fractured surfaces of rapidly quenched and sintered NdFeB magnets, it is found that the Nd-rich phases in the grain boundaries are different in these two kinds of magnets. In rapidly quenched NdFeB magnets, the Nd-rich phase is mainly Nd-Fe binary (Nd:Fe 2-3:1) without oxygen. In sintered NdFeB magnets, the Nd-rich phase is mainly Nd-Fe binary (Nd:Fe 2-3:1) without oxygen. In sintered NdFeB magnets, the Nd-rich phase is Nd-Fe-O (Nd:Fe:O 2-3:1:1). There are many Nd oxide particles (Nd:O about 1:1-1.5) of 1 mu m in diameter in the sintered NdFeB, but not in the rapidly-quenched samples.<>