Pr-Co magnets; Phase transformation; Magnetic properties

关键词:Pr-Co magnets; Phase transformation; Magnetic properties; Mechanical alloying
摘要:<正>PrCo5-based nanograin PrxCo100-x (x=14~22) alloys with high coercivity were synthesized by mechanical alloying Neodymium Magnets
http://www.999magnet.com/products/110-sintered-neodymium-magnets and subsequent annealing. The crystallization, phase components and magnetic properties of the alloys were investigated systematically. The main phase of the alloy for x=14 is Pr2Co17 with rhombohedral Th2Zn17-type. The amount of the Pr2Co17 phase decreases with increasing Pr content, and a nearly single phase PrCo5 with hexagonal CaCu5-type is formed in Pr19Co81 alloy. Further increase in the Pr content leads to the formation of another magnetically hard Pr2Co7 phase with its Curie temperature about 350℃. Remanences decrease monotonously with increasing Pr content, whereas the coercivities increase, reaching a maximum of 2040 kA/m (25.6 kOe) in Pr19Co81 powders milled for 5 h and annealed at 973 K for 2 min, and then decrease for higher Pr content. The high coercivity is attributed to the high anisotropy field of the PrCo5 phase and its nanoscale grain size.