MAGNETIC PHASES IN AS-CAST AND 600-DEGREES-C ANNEALED ND80FE15(B1-XCX)(5) ALLOYS LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-1.0)

Magnetic and microstructural studies have been performed in as-cast an d annealed Nd80Fe15(B1-xCx)(5), 0.0 less than or equal to x less than or equal to 1.0, alloys in order to study the magnetic phases that for m upon C addition. In as-cast samples, metastable A(1) (T-c = 245 degr ees C; H-i(c) around 4-5 kOe) was the predominant phase in the whole c omposition range, with intrinsic properties that were not affected wit h increasing C content. Up to x = 0.5 this phase coexists with a stabl e minor magnetic phase referred to as A(3) (T-c = 290 degrees C). Upon annealing at 600 degrees C A(1) dissolves and the following stable ph ases were detected: (a) Nd2Fe14B and A(3) for 0.0 less than or equal t o x less than or equal to 0.75; (b) an unknown stable phase D-1 with c oercivity around 2.2 kOe and Curie temperature of 260 degrees C for x = 1.0. This phase is the predominant one for annealing times less than 2 h, while for longer treatments an additional phase with T-c = 55 de grees C appears. Scanning electron microscopy studies were carried out to characterize the Nd80Fe15C5 in as-cast and annealed states. The D- 1 phase is believed to be a platelet-like phase with Fe:Nd ratio large r than unity.