EFFECT OF ANNEALING ATMOSPHERE ON MICROST RUCTURE AND MAGNETIC-PROPERTIES OF HIGH SI-FE ALLOYS

Structure and magnetic properties of rapidly solidified 6.5 mass%Si-Fe alloy ribbons were studied by controlling the atmosphere during heat treatment. The ribbons were annealed in three kinds of atmosphere list ed as below. (1) in the vacuum atmosphere for 3.6 ks at 1448 K (2) in the sulfur atmosphere for 3.6 ks at 1448 K (3) in the vacuum atmospher e for 180 s at 1373 K and the sulfur atmosphere for 3.6 ks at 1448 K T he structure of ribbon, which were showed random structure at as prepa red state, was developed into (110) texture by the heat treatment (1). On the contrary, the structure was developed into (100) texture by th e heat treatment (2). In the case of the heat treatment (3), the struc ture of ribbon was also developed into (100) texture and the grain siz e was large such as 2.5-5 mm, as compared with heat treatment (1) and (2). The coercive force decreased to 2-4 A/m remarkably.