Wide iron-based amorphous alloy, precursor to nanocrystalline alloy

Abstract

An iron-based soft magnetic alloy greater than 63.5 mm in width, a thickness between 13 and 20 microns and having a composition represented by the following formula:
(Fe.sub.1-aM.sub.a).sub.100-x-y-z-p-q-rCu.sub.xSi.sub.yB.sub.zM.sub.pM.sub.qX.sub.r
wherein M is Co and/or Ni, M is at least one element selected from the group consisting of Nb, W, Ta, Zr, Hf, Ti and Mo, M is at least one element selected from the group consisting of V, Cr, Mn, Al, elements in the platinum group, Sc, Y, rare earth elements, Au, Zn, Sn and Re, X is at least one element selected from the group consisting of C, Ge, P, Ga, Sb, In, Be and As, and a, x, y, z, p, q and r respectively satisfy 0a0.5, 0.1x3, 0y30, 1z25, 5y+z30, 0.1p30, q10 and r10, the alloy being at least 50% crystalline with an average particle size of 100 nm or less. This alloy has low core loss, high permeability and low magnetostriction.

Claims

1. A nanocrystalline alloy formed by annealing an iron-based amorphous alloy, the iron-based amorphous alloy comprising: a composition represented by the following formula:
(Fe.sub.1-aM.sub.a).sub.100-x-y-z-p-q-rCu.sub.xSi.sub.yB.sub.zM.sub.pM.sub.qX.sub.r wherein M is Co and/or Ni; M is at least one element selected from the group consisting of Nb, W, Ta, Zr, Hf, Ti, and Mo; M is at least one element selected from the group consisting of V, Cr, Mn, Al, elements in the platinum group, Sc, Y, rare earth elements, Au, Zn, Sn, and Re; X is at least one element selected from the group consisting of C, Ge, P, Ga, Sb, In, Be, and As; and a, x, y, z, p, q and r respectively satisfy 0a0.5, 0.1x3, 0y30, 1z25, 5y+z30, 0.1p30, q10 and r10, wherein the iron-based amorphous alloy is manufactured using single roller quenching, wherein the iron-based amorphous alloy has a width greater than 63.5 mm, a thickness in the range of 13 to 20 m, wherein the thickness variation across the width direction of the iron-based amorphous alloy is less than +/15% of the total thickness, and wherein the nanocrystalline alloy has a nanocrystalline structure and a saturation magnetic induction greater than 1.15 T.

2. The nanocrystalline alloy of claim 1, wherein the iron-based amorphous alloy has at least two crystallization events or temperatures and wherein the nanocrystalline alloy has a crystalline particle size less than 100 nm formed after annealing the iron-based amorphous alloy between a first crystallization temperature and a second crystallization temperature.

3. The nanocrystalline alloy of claim 1, comprises a portion of a device selected from the group consisting of saturation inductors or magnetic switches, electromagnetic interference filters, transformers, current sensors, and ground fault current interrupt sensors.

4. A method for manufacturing a nanocrystalline alloy, the method comprising: selecting a composition represented by the following formula:
(Fe.sub.1-aM.sub.a).sub.100-x-y-z-p-q-rCu.sub.xSi.sub.yB.sub.zM.sub.pM.sub.qX.sub.r wherein M is Co and/or Ni; M is at least one element selected from the group consisting of Nb, W, Ta, Zr, Hf, Ti, and Mo; M is at least one element selected from the group consisting of V, Cr, Mn, Al, elements in the platinum group, Sc, Y, rare earth elements, Au, Zn, Sn, and Re; X is at least one element selected from the group consisting of C, Ge, P, Ga, Sb, In, Be, and As; and a, x, y, z, p, q and r respectively satisfy 0a0.5, 0.1x3, 0y30, 1z25, 5y+z30, 0.1p30, q10 and r10, quenching using a single roller to obtain an iron-based amorphous alloy having a width greater than 63.5 mm, a thickness in the range of 13 to 20 m, a thickness variation across the width direction of the iron-based amorphous alloy of less than +/15% of the total thickness, and annealing the iron-based amorphous alloy to obtain a nanocrystalline alloy having a nanocrystalline structure and a saturation magnetic induction greater than 1.15 T.

5. The method of claim 4, wherein the iron-based amorphous alloy has at least two crystallization events or temperatures and wherein the nanocrystalline alloy has a crystalline particle size less than 100 nm formed after annealing the iron-based amorphous alloy between a first crystallization temperature and a second crystallization temperature for a time varying between 10 seconds to 4 hours.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1schematic of manufacturing method of the iron based amorphous precursor ribbon of the present invention where 1 is the induction melting furnace, 2 is the holding furnace, 3 is the rotating quench wheel, 4 is the thread up brush and 5 is the winder and spool.

(2) FIG. 2plot of thickness variation in the width direction of ribbon when using the nozzle slot expansion control methods of the present invention.

(3) FIG. 3plot of thickness variation in the width direction of ribbon when using the using the prior art without accounting for the thermal deformation of the nozzle and casting wheel.

DETAILED DESCRIPTION OF THE DRAWINGS

(4) The invention will be described in further detail in combination with the figures and embodiments.

(5) For the composition of the iron-based amorphous alloy cast as a precursor to the nanocrystalline ribbon, the raw materials consist of pure iron, ferroboron, ferrosilicon, ferroniobium, and pure copper. These raw materials are melted in an induction furnace preferably heated to 1400 C. where the molten metal is held and refined, allowing for incidental impurities to rise to the top of the melt, which can be removed as solid slag as shown in FIG. 1 step 1. The molten metal is then transferred to a holding furnace as shown in FIG. 1 step 2.

(6) The molten metal is fed from the holding furnace through the ceramic casting nozzle with a controlled constant pressure flow rate. The nozzle to quench wheel distance is preferably between 150 and 300 microns in distance. The molten metal puddle bridges this gap and a stable molten puddle is formed from which the metal solidifies and a continuous ribbon is cast as shown in FIG. 1 step 3.

(7) The ribbon is removed from the quench wheel and caught in a thread-up brush as shown in FIG. 1 step 4. The ribbon is then transferred at a synchronous speed of the quench wheel rotation to the winding device as shown in FIG. 1 step 5.

(8) The recommended casting speed is preferably between 25 and 35 m/s with 28 to 30 m/s being more preferred. The ribbon thickness is preferably between 13 and 20 microns with 16 to 18 microns being more preferred. The ribbon thickness uniformity across the width direction preferably shows variations less than +/15% of the total ribbon thickness. FIG. 2 shows the typical thickness of the cast ribbon measured with a 1 cm anvil checked at 1 cm intervals across the width direction of the ribbon. The ceramic nozzle is preferably mechanically clamped at various positions across the nozzle width to control the nozzle slot opening such that it matches the quench wheel deformation and maintains a flat ribbon profile. FIG. 3 shows a similar cast ribbon profile when the nozzle is not mechanically clamped and large thickness variations occur across the width to the center of the ribbon.

(9) The nozzle could also be contoured to match the quench wheel shape to minimize ribbon profile variations. Here, the gap height spacing between the nozzle and the wheel is controlled to maintain a flat ribbon profile. However, clamping the nozzle is preferred due to the added labor and machining needed to contour the shape into the nozzle.

(10) Through implementing the technical solutions of the present solution the iron base amorphous precursor ribbon of width greater than 63.5 mm can be heat treated into a nanocrystalline state with excellent soft magnetic properties. The ribbon shown in FIG. 2 was slit from the parent material of 142 mm was slit at widths of 20 mm from the center and from each edge and formed into small toroids for magnetic testing. The ribbon was annealed in a furnace at 550 C. for one hour to induce the nanocrystalline state.

(11) Table 1 shows the resulting average magnetic properties of the three toroids and the variation between the edge and center portion of the ribbon after being annealed at 550 degrees C. in an inert atmosphere oven. The average induction levels at an applied field of 800 A/m is 1.2 T with a variation of on 0.5 T. The coercivity is 0.71 A/m with a variation of 0.25 A/m. The permeabilities are 104000, 75000, and 13000 with variation of 10000, 5000, and 3000 when tested at 1 kHz, 10 kHz, and 100 kHz respectively.

(12) TABLE-US-00001 TABLE 1 Magnetic properties of the nanocrystaline toroidal cores with typical variability across the cast width direction for an embodiment of the present invention. Toroid Wt. (g) B800 (T) Hc (A/m) @ 1 kHz @ 10 kHz @ 100 kHz 11 +/ 0.5 1.2 +/ 0.05 0.71 +/ 0.25 104000 +/ 10000 75000 +/ 5000 13000 +/ 3000

(13) Table 2 shows the chemical composition in weight percent, the ribbon width and thickness of an embodiment of the present invention.

(14) TABLE-US-00002 TABLE 2 Ribbon chemistry, width and thickness for an embodiment of the present invention. Alloy chemistry Ribbon width Ribbon Thickness (wt %) (mm) (microns) Fe83Si8.6B1.4Nb5.5Cu1.3 142 18

(15) Table 3 shows the chemical composition in weight percent, the ribbon width and thickness of an embodiment of the present invention.

(16) TABLE-US-00003 TABLE 3 Ribbon chemistry, width and thickness for an embodiment of the present invention. Alloy chemistry Ribbon width Ribbon Thickness (wt %) (mm) (microns) Fe83Si8.6B1.4Nb5.5Cu1.3 142 18 Fe83Si8.6B1.4Nb5.5Cu1.3 142 15 Fe83Si8.6B1.4Nb5.5Cu1.3 216 18 Fe79.5Si6.2B2.1Nb5.2Cu1.3Ni5.9 142 18 Fe83Si8.6B1.4Mo5.6Cu1.3 51 17

(17) Table 4 shows the chemistry and crystallization temperatures for the initial and secondary stages for an embodiment of the present invention. Typically the ribbon is wound into a toroidal core or slit and stacked into a shape and possibly impregnated with glue in an electronic application. The core or stacked shape is then annealed at a temperature above the onset crystallization point but below the secondary crystallization point to induce the nanocrystalline phase.

(18) TABLE-US-00004 TABLE 4 Ribbon chemistry and crystallization temperatures for the initial and secondary stages for an embodiment of the present invention. Onset Secondary Alloy chemistry Crystallization Crystallization (wt %) T (C.) T (C.) Fe83Si8.6B1.4Nb5.5Cu1.3 540 650 Fe79.5Si6.2B2.1Nb5.2Cu1.3Ni5.9 530 650 Fe83Si8.6B1.4Mo5.6Cu1.3 515 650