The electrical resistivity of two NdFeB samples, Nd15FeT7B8 and Nd5Fe62B33, has been studied with increasing and decreasing temperatures between 4 K and 1,200 K. The magnetization of these two samples was measured between 300 K and 1,000 K. According to experimental data, the a-Fe is manifestly precipitated above roughly 900 K. The magnetic phase transition near 570 K identified by X-ray analysis is due to the tetragonal Nd2Fe14 B phase.