• Carvalho, Patrícia Almeida
• Gonçalves, António Pereira
• Pereira, Laura C. J.
• Colaço, Rogério
• Nunes, Daniela
• Hosson, Jeff Th M. De

Abstract

<p>The microstructure and magnetic domain configuration of splat-quenched YFe₁₁Ti aggregates have been investigated by transmission electron microscopy, Lorentz microscopy and magnetic force microscopy. The splat-quenched material adopted essentially the ThMn₁₂-type structure and displayed an equiaxed polycrystalline microstructure with a scattered presence of α-Fe(Ti). Lorentz microscopy and magnetic force microscopy showed that the critical size for single-domain behaviour in the splat-quenched aggregates is close to 100 nm. Annealing induced a decrease in coercivity justified by overall grain coarsening and additional α-Fe(Ti) formation. Lorentz microscopy evidenced stripe/maze patterns in coarse YFe₁₁Ti grains; while coarse α-Fe(Ti) grains exhibited vortex configurations resulting from accommodation to the demagnetizing fields of adjacent YFe₁₁Ti grains. Planar defects with twin appearance and thermal antiphase boundaries have been observed in YFe₁₁Ti grains but showed no interaction with domain walls. On the other hand, grain boundaries and in particular grain-boundary triple joints exhibited a moderate pinning effect.</p>

Topics

• impedance spectroscopy
• grain
• transmission electron microscopy
• defect
• annealing
• coercivity
• polycrystalline microstructure