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-Fe
3B+α-Fe. The single α-Fe(B) phase was not observed. The transition temperature from t-Fe
3B to stable (α-Fe+t-Fe
2B) 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-Fe
2B 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-Fe
3B and amorphous phases. The lattice parameter of the phase was 0.2861
0 nm which was smaller than that of pure iron by 2/1000, indicating the substitutional occupation of boron atoms in the bcc lattice.
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