Primary ultrafine-crystalline alloy ribbon and its cutting method, and nano-crystalline, soft magnetic alloy ribbon and magnetic device using it

A primary ultrafine-crystalline alloy ribbon having a composition represented by the general formula of Fe100-x-y-zAxByXz, wherein A is Cu and/or Au, X is at least one element selected from the group consisting of Si, S, C, P, Al, Ge, Ga and Be, and x, y and z are numbers meeting the conditions of 0<x≦5, 10≦y≦22, 0≦z≦10, and x+y+z≦25, respectively, when expressed by atomic %, and having a structure in which ultrafine crystal grains having an average grain size of 30 nm or less are dispersed in a proportion of 5-30% by volume in an amorphous matrix;

• said primary ultrafine-crystalline alloy ribbon having a width of 10 mm or more and a thickness of 15 μm or more, with thickness difference of 2 μm or less in a transverse direction;
• said primary ultrafine-crystalline alloy ribbon having Vickers hardness Hv (measured at a load of 100 g) of 850-1150 in both center and side portions in a transverse direction;
• and
• the difference of Vickers hardness Hv (measured at a load of 100 g) between the center portion and the side portions being 150 or less.

A method for cutting a primary ultrafine-crystalline alloy ribbon having a structure in which ultrafine crystal grains having an average grain size of 30 nm or less are dispersed in a proportion of 5-30% by volume in an amorphous matrix;

• said ribbon having a width of 10 mm or more and a thickness of 15 μm or more, with thickness difference being 2 μm or less in a transverse direction, and having Vickers hardness Hv (measured at a load of 100 g) of 850-1150 in both center and side portions in a transverse direction, the difference of Vickers hardness Hv (measured at a load of 100 g) between the center portion and the side portions being 150 or less;
• which comprises the steps of
• placing said primary ultrafine-crystalline alloy ribbon on a soft base deformable to an acute angle by local pressing;
• bringing a cutter blade into horizontal contact with a surface of said primary ultrafine-crystalline alloy ribbon;
• and
• pressing said cutter to said primary ultrafine-crystalline alloy ribbon to apply uniform pressure thereto, thereby bending said primary ultrafine-crystalline alloy ribbon along a blade edge of said cutter to fracture-cut it.

A nanocrystalline, soft magnetic alloy ribbon obtained by heat-treating a primary ultrafine-crystalline alloy ribbon having a composition represented by the general formula of Fe100-x-y-zAxByXz, wherein A is Cu and/or Au, X is at least one element selected from the group consisting of Si, S, C, P, Al, Ge, Ga and Be, and x, y and z are numbers meeting the conditions of 0<x≦5, 10≦y≦22, 0≦z≦10, and x+y+z≦25, respectively, when expressed by atomic %, and having a structure in which ultrafine crystal grains having an average grain size of 30 nm or less are dispersed in a proportion of 5-30% by volume in an amorphous matrix;

• said primary ultrafine-crystalline alloy ribbon having a width of 10 mm or more and a thickness of 15 μm or more, with thickness difference of 2 μm or less in a transverse direction, and Vickers hardness Hv (measured at a load of 100 g) of 850-1150 in both center and side portions in a transverse direction;
• the difference of Vickers hardness Hv (measured at a load of 100 g) between the center portion and the side portions being 150 or less;
• said nanocrystalline, soft magnetic alloy ribbon having a structure in which fine crystal grains having an average grain size of 60 nm or less are dispersed in a proportion of 30% or more by volume in an amorphous matrix, and being fracture-cut along a cutter blade in horizontal contact with a surface of said ribbon before or after the heat treatment;
• when notches are generated along the fracture-cut portion of said ribbon, the percentage of said notches being 5% or less, which is determined by the following formula:
• Percentage of notches=(Dav/D)×100(%),
• wherein D is the width of said ribbon, Dav is an average depth of said notches, which is obtained by dividing the total area of said notches by the width D of said ribbon.