Reresearch On Sm-co/Fe₇Co₃Two-phase Nanocomposite Magnets

Currently, the method that how to get the permanent magnets with higher energyproduct has been widely studied by materials scientists. Wherein, two-phasenano-composite magnets has drawn the greatest attention for its unique exchange-coupledeffect, which has the most potential to become the next generation of permanent magnets.In addition, with the development of heavy industry in areas such as aerospace anddefense，it requests the magnetic element should be working under high temperatureconditions. Sm-Co-based rare-earth permanent magnets has high Curie temperature andanisotropy field, so the nano-composite materials based on Sm-Co has high magneticproperties and high stability under high temperature. With those superiority, it can be usedin magnetic element which works under high temperature environment.In this paper, we fabricated different kinds of Sm-Co ribbons by melt spinningquenching and get Fe7Co3powder with the method of liquid nitrogen atomization, thenSm-Co/Fe7Co3nano-composite powder was fabricated by high-energy ball millingtechnology.Also, different hard magnetism, the proportion of soft magnetism, trace element,surfactant and time of ball milling may have different influences on the phase, magneticproperties, morphology and sizes of composite powder prepared by ball milling, whichhave been studied.The results shows that the phase structures of the powder is the original Sm-Co phaseand Fe7Co3phase, the size of the powder reduced significantly. The magnetic energy ofSm2Co17/Fe7Co3and Sm(Co,Cu,Fe,Zr)7/Fe7Co3powder improved substantially. With theincreasing of the proportion of the soft phase, the composite powder gradually exhibit softmagnetic properties. It gets the highest magnetic energy when10%wt soft magnets isinvolved. With the extension of milling time, the coercivity of the SmCo5/Fe7Co3andSm(Co,Cu,Fe,Zr)7/Fe7Co3composite powder is reducing. But the composite powder ofSm2Co17/Fe7Co3is increasing. Under the argon protection, the powder particles reunion andthe magnetic properties is bad. When n-heptane and surfactant was used as surfactant, weobtained lamella with smaller particle sizes and higher magnetic properties. Adding traceDy, the coercivity increases and the remanence decreased slightly.