High-temperature magnetization and bulk magnetostriction investigation of Ti and Nb addition to Fe70Co30 alloy

Lowering the Co content of the equiatomic Fe–Co alloys is of economic interest. The greatest interest is the application on electric motors, since the high-saturation magnetization level provides higher torques. In the present work, Fe 70 Co 30 alloys with the addition of Ti and Nb were studied to improve magnetic properties. The alloys (Fe 0.7 Co 0.3 ) 97 Ti 3 , (Fe 0.7 Co 0.3 ) 99 Nb 1 , and (Fe 0.7 Co 0.3 ) 96 Ti 3 Nb 1 were produced, and the effects of Ti and Nb addition on the Fe 70 Co 30 alloy microstructure and magnetic properties were studied. The addition of 1% of Nb + 3% of Ti to the Fe 70 Co 30 alloy reduced most of the saturation magnetization polarization (from 2.34 to 2.14 T at 300 K), but the saturation magnetic polarization P s is almost the same of pure Fe, although the Curie temperature is 195 K higher. The addition of only Ti or only Nb resulted in P s even higher than 2.14 T and (Fe 0.7 Co 0.3 ) 99 Nb 1 presents the highest P s . The quaternary alloy has the lowest value of H c = 362 A m −1 and λ s = 54 × 10 −6 , though the (Fe 0.7 Co 0.3 ) 99 Nb 1 has the highest H c = 1790 A m −1 , the highest P s = 2.23 T, and the lowest saturation magnetostriction λ s = 42.7 × 10 −6 . The alloy’s spin wave stiffnesses were determined from saturation magnetization versus temperature curves.