Influence of intermediate annealing on abnormal Goss grain growth in the rolled columnar-grained Fe-Ga-Al alloys

Abstract

Magnetostrictive Fe82Ga4.5Al13.5 sheets with 0.1at% NbC were prepared from directional solidified alloys with <001> preferred orientation. The slabs were hot rolled at 650°C and warm rolled at 500°C. Then some warm-rolled sheets were annealed intermediately at 850°C for 5min but the others not. After that, all the sheets were cold rolled to a final thickness of ∼0.3mm. The microstructures, the textures and the distributions of second phase particles in the primary recrystallized samples were investigated. With intermediate annealing, the inhomogeneous microstructure was improved remarkably and strong Goss ({110}<001>) and γ-fiber (<111>//normal direction [ND]) textures were produced in the primary recrystallized samples. But, an evident disadvantage in size and quantity was observed for Goss grains in the primary recrystallized sample without intermediate annealing. After a final annealing, the final textures and magnetostrictions of samples with and without intermediate annealing were characterized. For samples without intermediate annealing, abnormal growth of {113} grains occurred and deteriorated the magnetostriction. In contrast, abnormal Goss grain growth occurred completely in samples with intermediate annealing and led to saturation magnetostriction as high as 156ppm.