Structure, phase transformation and magnetic properties of Nd–Fe–C alloys made by mechanical alloying and subsequent annealing

An investigation of structural and magnetic properties of the Nd16Co72-xRu xC11B coro-carbides

“…In Nd-Fe-C-based alloys the remanence and maximum energy product are improved by increasing both Nd and C contents [22]. An increase in the C content increases the amount of Nd 2 Fe 14 C. However, a high C content also increases the α-Fe content.…”

“…According to the results of Sui et al [22], in order to make Nd 2 Fe 14 C the main phase the Nd:C ratio must be kept within a certain range, because too little C leads to the formation of Nd 2 Fe 1 4C x as the main phase, and too much C increases the α-Fe content inhibiting the formation of Nd 2 Fe 14 C. The tetragonal Nd 2 Fe 14 C phase is formed at comparatively low temperatures (800 • C) contrarily to the tetragonal Nd 2 Fe 14 B phase which forms at a comparatively high temperature directly from the melt. Primary cristallization products α-Fe and R 2 Fe 17 or a derivative of it [23,24].…”

Decomposition of B4C and magnetic properties of Nd–Fe–(B,C) alloys synthesized by mechanical alloying

“…The powder mixtures of 10 g were sealed in a hardened steel vial with steel balls of 12 mm diameter in a high-purity argon-filled glove box. Mechanical alloying of the mixtures was performed in a high-energy ball mill, which was rotated in two dimensions perpendicular to the horizontal plane [7][8][9]. The rotation speed of the mill was close to 800 rpm.…”

“…Mechanical alloying (MA) has been proved to be a powerful technique for synthesizing magnetic compounds such as Nd 2 Fe 14 B, SmFe 7 N δ and Nd 2 Fe 14 C [6][7][8]. In previous work, Nd-Fe-(B,C) alloys were prepared with pure B and C powders, and the influence of C content on their structure and magnetic properties was systematically studied [8,9]. Recently, by using MA and subsequent heat-treatment, the * Corresponding author.…”

Enhanced coercivity in Nd–Fe–C alloys prepared by a re-milling process

“…Sui et al [17,19] reported that the annealing-temperature range for formation of Nd 2 Fe 14 C could be enlarged by the mechanical alloying and an intrinsic coercivity of 7.5 kOe was achieved in mechanically alloyed Nd-Fe-C magnets. Meanwhile, it was found that too low Nd content led to Nd 2 Fe 17 C x as the main phase, and for higher Nd content, Nd first reacted with C to form Nd-carbides so that a large amount of Nd 2 Fe 17 C x phase coexisted [19]. It is undoubted that the nonmagnetic Nd-carbides will deteriorate magnetic properties of permanent magnets.…”