Influence of phase transformation on interfacial activity and bend sensitivity of rapidly quenched Fe_77.5Si_7.5B₁₅/Co_72.5Si_12.5B₁₅ bilayered magnetostrictive ribbons

Rapidly quenched bilayer magnetostrictive ribbons have been prepared and characterized to investigate phase transformations, interfacial activity and their potentiality as bend sensors. The bilayer ribbons were processed in a way to make the positively magnetostrictive layer Fe_77.5Si_7.5B₁₅ as the free surface while negatively magnetostrictive Co_72.5Si_12.5B₁₅ layer as the one in contact with the quenching copper wheel. Elemental concentration profiles obtained through electron probe microanalysis (EPMA) revealed synergistic variation in Fe and Co content at the interface. Devitrification process was also observed from atomic migrations and combinations influencing the interface width. Configuration of the bent layers showed interesting bending parameter output which could be further enhanced through stress relaxation. A detrimental effect of devitrification on bend sensitivity of rapidly quenched bilayers was also displayed. - Highlights: • Melt spun bilayered ribbons of Fe_77.5Si_7.5B₁₅ and Co_72.5Si_12.5B₁₅ alloys were prepared. • Superior bend sensitivity in bilayered ribbons were observed through stress relief. • Synergistic Fe and Co interfacial diffusion occurred across Fe and Co alloy bilayer. • Quantitative analysis elucidates diffusion across interface zone of bilayer. • Bend sensor configuration has been suggested based on functional gradation