Temperature and annealing dependencies of magnetostriction constant in a Co-rich zero-magnetostrictive metallic glass

Isochronal and isothermal studies have been performed on Co-rich nearly-zero-magnetostrictive go-Fe-V-Si-B metallic glass, and the saturation magnetostriction constant λshas been determined for the 'as quenched' and annealed states in the temparature range 30-240°C. The temperature dependence of λscan be satisfactorily explained in terms of two-ion and single-ion contributions, i.e.,λₛ(T) = a[μ₀Mₛ(T)]² + b[μ₀Mₛ(T)]³. We find that the smaller variation λsbefore crystallization comes from the synchronous variation of a and -b; and that initial crystallization causes λsto decrease faster because of the rapid increase in the coefficient -b. While the kinetic behaviour of λsis found to be temperature dependent in a complex way, the coefficients a and b are found to exhibit a simple dependence on the kinetics. Substitution with Ni and V for Fe in Co-Fe-Si-B is found to decrease the value of a and b so as to realize a better permeability performance. As far we know the temperature dependence of the coefficients a and b reported here are the first such studies to be presented.