Effect of B or C Addition on Phase Transformation and Magnetic Properties of Pr_(17)Co_(83-x)T_x (T = B or C, x = 0-10) Powders Prepared by Mechanical Alloying

摘要

The phase transformation and magnetic properties of Pr_(17)Co_(83-x)T_x (T = B or C, x = 0 - 10) alloy powders prepared by mechanical alloying and subsequent annealing have been studied systematically. After annealed at 650°C for 2 min, according to the results of X-ray diffraction and a.c. susceptibilities, the main phase of Pr_(17)Co_(83) alloy powders is a crystalline PrCo_5 phase with hexagonal CaCu_5-type structure. The Pr_2Co_(14)B phase with tetragonal Nd_2Fe_(14)B-type structure appears when the B content increases. The appearance of the Pr_2Co_(14)B phase is confirmed also by its spin reorientation transition temperature T_(sr)( = 390°C). The main phases become a mixture of Pr_2Co_(14)B and PrCo_5 phases for the powders for B substitution in the range of x = 2 - 8. In the powders with x = 10, PrCo_4B phase with hexagonal CeCo_4B-type structure becomes the main phase. In the case of the C addition, however, the powders are composed of PrCo_5 and PrCo_2C_x phases. The remanence and the maximum energy product decrease monotonously with increasing the B or C content.