Zhang, MC (reprint author), Univ Sci & Technol Beijing, State Key Lab Adv Met & Mat, Beijing 100083, Peoples R China.
The micro-defects of Fe81Ga19 ribbons have been investigated by the positron annihilation technique. It has been found that the defects of mono-vacancies and vacancy-clusters exist in the melt-spun ribbons of Fe81Ga19 alloy and the relative concentrations of them may be changed by heat treatment. The heat treatment leads to variations of magnetostrictive strains. As high as - 3000 ppm strains have been obtained in the ribbons annealed at 700 degrees C, surpass the strain values of Tb-Dy-Fe alloys. Experimental results prove that magnetostrictive strains of Fe81Ga19 ribbons are related to the atomic vacancies and vacancy-clusters. (c) 2006 Elsevier B.V. All rights reserved.