Determination of density and vacancy concentration in rapidly solidified FeAl ribbons

In order to observe an anomalously large number of thermal vacancies retained in B2-type FeAl, an FeAl alloy is rapidly solidified into ribbons by a conventional melt-spinning technique, and the density and vacancy concentration of these ribbons are determined by an Archimedes water immersion technique and x-ray diffraction method. The lattice constant of as-spun ribbon, which has already B2-type ordered structure regardless of the rapid solidification by melt-spinning, is 2.8992×10−10 m. This is smaller than that of water-quenched FeAl alloys previously reported, indicating lattice relaxation due to the existence of numerous thermal vacancies. The total vacancy concentration of as-spun ribbons is estimated to be approximately 1.38±0.15%, which is several hundred times as high as that of pure metals and disordered alloys near the melting point.