Effect Of Ball Milling Time And Hard Phase Composition On Microstructure And Properties Of SmCo/?-Fe(Co) Magnets

SmCo based nanocomposite permanent magnets have high coercivity and high temperature stability,which may be widely used in various fields in the future.The commonly method for preparing SmCo based nanocomposite permanent magnets is high energy ball milling,but the technological parameters of high energy ball milling have great influence on the structure and properties of the magnets.SmCo/alpha-Fe?Co?nanocomposite magnets were prepared by high energy ball milling and thermal annealing,in this work.By using the techniques of X-ray diffraction?XRD?and vibrating sample magnetometer?VSM?,the nanocomposite magnets of SmCo/?-Fe?Co?is carried out the following two aspects research work:The effect of milling time on the Sm Co/?-Fe?Co?nanocomposite permanent magnets has been studied.Handling different milling time separately,the SmCo alloy was found: with the longer of milling time,the degree of amorphization of hard phase in ball milled powder increased.,the soft magnetic phase volume fraction was becoming larger,the Fe:Co atomic ratio in soft magnetic phase decreased,and the Sm:Co atomic ratio in hard phase increased.To anneal the ball milled powder at different temperature,it was found that within the range of400? to 580? annealing the phase of SmCo3 is becoming more with the milling time delay.Therefore,controling the magnet phases can take the method of changing the milling time,The best magnetic properties :?BH?max= 11.448 MGOe can be obtained after the ball milling time of 5.5h and 580? anealing within 10 min.The effect of composition of hard magnetic phase on the SmCo/?-Fe?Co?nanocomposite permanent magnets has been studied.Doping of Fe,Cu,Zr elements in the hard phase,then taking 4.5h ball milling in the alloy.The results showes that doping of Fe,Cu,Zr elements improve the amorphization degree of hard phase and the soft magnetic phase volume fraction in ball milled powder,At the same time,Sm:Co atomic ratio in the hard magnetic phase improved.It was found that doping of Fe,Cu and Zr elements decreased the crystallization temperature of the magnets.The hard magnetic phase doped of Fe,Cu,Zr elements within the range of 450? to 580? annealing precipitated more SmCo₃ phase.Above 650 ? annealing the SmCo₃ phase transformed into SmCo7 phase.However,without the addition of Fe,Cu and Zr elements,the precipitation is SmCo7 in the hard phase in the whole annealing process.The addition of Fe,Cu and Zr elements obviously improved the coercivity of the magnets.The best magnetic properties :?BH?_max= 11.024 MGOe can be obtained after the ball milling time of 4.5h and 580? anealing within 10 min.