Evolution of Microstructure and Magnetic Properties of Isotropic Alnico 8 Ribbons with Various Ti Contents

Optimizing the spinodal decomposition structure in Alnico magnets is a very effective way to improve the performance. Some elemental additives are extremely sensitive to the spinodal decomposition process. In this manuscript, the evolution of spinodal decomposition structure in isotropic Alnico 8 ribbons with various Ti contents and its effects on magnetic properties and service performance are investigated. Alnico 8 ribbons with nominal composition of different Ti content (3.5 wt%-7.5 wt%) were prepared by melt-spinning and simplified heat treatment. The optimum magnetic properties of the ribbons such as intrinsic coercivity, H_cj=860 Oe, remanence magnetization, B_r =5.89 kGs, and maximum magnetic energy product, (BH)_max=1.2 MGOe are obtained for 5.5 wt% Ti. The ribbons show excellent temperature stability, their magnetic properties are 100% reversible up to 800 K and can be maintained above 85% at 800 K. The increase of Ti decreases the Curie temperature of the ribbons slightly. The evolution of spinodal decomposition phases and its influence mechanisms on magnetic properties are studied.