Nanocrystalline magnetic conductive sheet for wireless charging and preparation method therefor

A preparation method of a nanocrystalline magnetic conductive sheet for wireless charging, comprising following steps:

• (1) preparing an alloy with a composition of Fe(100-y-z-α-β)CuyNbzSiαBβ (at. %) into an alloy strip with an initial state of amorphousness by a single roll rapid quenching method, wherein 0.7≤y≤1, 1.3≤z≤2, 4≤α≤14, 7≤β≤10, y+z+α+β≤23;
• (2) annealing an amorphous alloy strip according to a preset annealing process in step (1), to obtain a single-layer nanocrystalline strip, wherein saturation magnetic induction Bs of the single-layer nanocrystalline strip is greater than 1.24T;
• and
• (3) superimposing or not superimposing multiple single-layer nanocrystalline strips obtained in step (2), performing a magnetic fragmentation process on the single-layer nanocrystalline strip or a multi-layer nanocrystalline strip, and compositing or not compositing multiple single-layer nanocrystalline strips or multiple multi-layer nanocrystalline strips that are completed the magnetic fragmentation process by a compositing process, to obtain the nanocrystalline magnetic conductive sheet for wireless charging;
• wherein the preset annealing process is a twice annealing process in step (2), the twice annealing process comprises:
• raising temperature to T1 at a rate of 1 to 5° C. per minute, maintaining the temperature at T1 for 10 to 60 min, raising the temperature to T2 at a rate of 0.5 to 3° C. per minute, maintaining the temperature at T2 for 30 to 240 min, reducing the temperature to below 200° C., raising the temperature to T3 at the rate of 1 to 5° C. per minute, maintaining the temperature at T3 for 10 to 60 min, raising the temperature to T4 at the rate of 0.5 to 3° C. per minute, maintaining the temperature at T4 for 20 to 240 min, reducing the temperature to below 200° C., and taking materials out of a furnace, T1 and T3 are 0 to 50° C. below a crystallization onset temperature of the alloy strip, T2 and T4 are above a crystallization peak temperature of the alloy strip, T3 is 5 to 50° C. higher than T1, and T4 is 0 to 50° C. higher than T2.