Remarkable improvement of the coercivity of TbMn6Sn6 compound by melt-spinning process

The melt-spinning process has been carried out to improve the hard-magnetic properties of the TbMn6Sn6 compound. For the TbMn6Sn6 ribbons quenched at a rate of 40m/s and annealed at 545K for 30min, the highest coercivity of a bout 0.6T is achieved at room temperature, which is much higher than that o f the TbMn6Sn6 ingot. Both the ingot and the ribbon coercivities will incre ase with decreasing temperature. For ribbons, a greater improvement of coer civity has been made at lower temperatures. Microstructural studies show th e uniform nanocrystalline distribution in the TbMn6Sn6 ribbons and a small amount of Tb-rich phase in grain boundaries. The observed remarkable improv ement of magnetic hardening in ribbons is believed to arise from the unifor m nanoscale microstructure and the domain-wall pinning at the grain boundar ies.