Undercooling solidification method for preparing amorphous or nanocrystalline soft magnetic alloy with high Fe content

An undercooling solidification method for preparing an amorphous or nanocrystalline soft magnetic alloy, wherein a chemical formula of the amorphous or nanocrystalline soft magnetic alloy is FeSiBM, M is one or more of P, C, Nb, Zr, Hf, Mo, Y, Cu and Co;

• and an alloy is undercooled and solidified by means of glass fluxing combined with cyclical superheating, comprising:
• step 1:
• removing surface oxidation layers of raw materials of the alloy, cleaning the raw materials, weighing the raw materials according to a certain mass ratio, vacuumizing weighed raw materials in a vacuum induction melting furnace or vacuum arc melting furnace to at least 10−3 Pa, filling inert gas for protection, then melting the raw materials, and repeating melting for 4-6 times to obtain an alloy ingot;
• step 2:
• putting the alloy ingot into a crucible, and covering upper and lower surfaces with a glass purifying agent with a certain mass ratio so that the glass purifying agent completely covers the alloy ingot;
• step 3:
• after vacuumizing to at least 10−2 Pa, filling inert gas for protection, heating the alloy ingot to a molten state, then heating up to 1200-1500° C., preserving heat for 1-10 min to obtain a molten alloy, and turning off a heating electric power to make the molten alloy naturally cool;
• step 4:
• implementing a cycle process of “heating-heat preservation-solidification” for 3-6 times to obtain an undercooled and solidified alloy;
• step 5:
• solidifying the undercooled and solidified alloy into strips or powders through melt quenching or atomization;
• step 6:
• for the strips or powders, carrying out stress-relief annealing to obtain the amorphous soft magnetic alloy or carrying out crystallization annealing to obtain the nanocrystalline soft magnetic alloy;
• wherein a process for preparing the glass purifying agent comprises:
• weighing and placing powdered Na2B4O7 and B2O3 with a purity of not less than 98% in a corundum crucible respectively, firing at 400-600° C. for 1-8 h, then melting and firing at 800-1000° C. for 2-16 h, and mixing fired Na2B4O7 and B2O3 to obtain the glass purifying agent, wherein a mass ratio of Na2B4O7 to B2O3 is 1:1-20.