Fe<SUB>100−<I>X</I></SUB>B<I><SUB>X</SUB></I> (10≤<I>X</I>≤35) 非晶質合金の結晶化過程と磁気的性質およびα-FeへのBの強制固溶状況

Abstract

Amorphous specimens were prepared in the range of 10≤X≤35 at%B by a single roller method. The crystallization process and the B concentration dependence of the Curie temperature were examined by differential scanning calorimetry, X-ray diffraction, Mössbauer spectroscopy and magnetic measurement.Two step crystallization was observed in the specimens of X<17: Amor.→Amor.+B supersaturated bcc phase (α-Fe(B))→t-Fe3B+α-Fe. The single α-Fe(B) phase was not observed. The transition temperature from t-Fe3B to stable (α-Fe+t-Fe2B) sensitively depends on B content in the alloys. The crystallization temperature (TX) of the amorphous alloys was almost unchanged in 17≤X≤31, but increased remarkably in the high boron concentration of X≥33, where the decomposition products consisted of t-Fe2B and o-FeB. The Curie temperature (TC) of the amorphous phase is as low as 480 K at X=10, increased with increasing B content up to 820 K and then decreased in the high B concentration alloys of X>28.The single α-Fe(B) phase was not detected in the as quenched specimens of X=8 and 10. The phase coexisted with the o-Fe3B and amorphous phases. The lattice parameter of the phase was 0.28610 nm which was smaller than that of pure iron by 2/1000, indicating the substitutional occupation of boron atoms in the bcc lattice.