Undercooling solidification method for preparing amorphous or nanocrystalline soft magnetic alloy with high Fe content
The present invention provides an undercooling solidification method for preparing an amorphous or nanocrystalline soft magnetic alloy with high Fe content and the applicable amorphous or nanocrystalline alloy composition. The undercooling solidification is realized by glass purification combined with cyclical superheating or electromagnetic levitation melting. An undercooling solidification alloy is prepared into amorphous strips or powders through rapid quenching or atomization of melt, and can be prepared into a nanocrystalline alloy through heat treatment. The chemical formula of the applicable amorphous or nanocrystalline alloy is FeSiBM, wherein M is one or more of P, C, Nb, Mo, Zr, Hf, Mo, Y, Cu and Co. The amorphous or nanocrystalline alloy prepared by undercooling non-equilibrium solidification has the characteristics of high amorphous forming ability, high saturation magnetization and low coercive force.
1 . 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 Na 2 B 4 O 7 and B 2 O 3 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 Na 2 B 4 O 7 and B 2 O 3 to obtain the glass purifying agent, wherein a mass ratio of Na 2 B 4 O 7 to B 2 O 3 is 1:1-20.
2 . The undercooling solidification method according to claim 1 , wherein the inert gas is argon or nitrogen with a purity of not less than 99.9 vol %.
3 . The undercooling solidification method according to claim 1 , wherein a heat-resistance temperature of the crucible is not lower than 1400° C.
4 . The undercooling solidification method according to claim 1 , wherein a mass ratio of the glass purifying agent to the alloy ingot is 1:1-5.
5 . The undercooling solidification method according to claim 1 , wherein a total atomic percent of alloy elements is 100%, and a content of each element is as follows: Fe is 80.0-89.0 at %, Si is 1.0-9.0 at %, B is 3.0-12.0 at %, P is 0-5.0 at %, C is 0-5.0 at %, Nb is 0-3.0 at %, Zr is 0-3.0 at %, Hf is 0-3.0 at %, Mo is 0-3.0 at %, Y is 0-5.0 at %, Cu is 0-2.0 at % and Co is 0-16.0 at %.