Fe-Si-La alloy having excellent magneto-caloric properties

Abstract

Iron-silicon-lanthanum alloy (I) is claimed. Iron-silicon-lanthanum alloy of formula ((La 1 - a-M m aTR a 1) 1[(Fe 1 - b - b 1CobM b 1) 1 - x(Si 1 - cX c) x] 1 3(C dN eH 1 - d - e) y(R) z(l) f) (I) is claimed. M mlanthanum (22-26 wt.%), cerium (17-20 wt.%), neodymium (5-7 wt.%) or praseodymium (5-7 wt.%), where the mixture comprises up to 1 wt.% of impurities; TR : one or more rare earth family elements other than lanthanum; M : one or more d-transition elements of layers 3d, 4d and 5d; X : metalloid element comprising Ge, Al, B, Ga or Ln; R : Al, Ca, Mg, K or Na; l : two elements comprising O or S; a : 0-0.5; a1 : 0-0.2; b : 0-0.2; b1 : 0-0.4; c : 0-0.5; d : 0-1; e : 0-1; f : = 0.1; x : 0.09-0.13; y : 0.002-4; and z : 0.00005-0.1. Where indexes b, d, e, x and y are such that the alloy satisfying the relation of (6.143b(13(1-x))+4.437y[1-0.0614(d+e)]>= 1). INDEPENDENT CLAIMS are included for: (1) powder of the alloy having average granulometry of less than 1000 mu m, preferably less than 500 mu m, comprising at least two different alloys (A 1and A 2) having transition temperatures (Ttr 1, Ttr 2) and peak widths at mid-height (delta T(LMH1), delta T(LMH2)) and their curves with respect to their magnetic entropy variation (delta S m 1(T) and delta S m 2(T)) depends on their respective work ranges of (Ttr 1-delta T(LMH1), Ttr 1+delta T(LMH1)) and (Ttr 2-delta T(LMH2), Ttr 2+delta T(LMH2)) coinciding with each other; (2) manufacturing the alloy powder comprising developing a precursor of the alloy of which at least one of the carbon, nitrogen and / or hydrogen content is less than that of the final alloy (where y is 0), atomizing the molten form, without prior solidification to obtain a powder particles, casting and solidifying in the form of ingot, tape, thread or powder particles by solution annealing, optionally a slag or vacuum remelting, fragmenting the ingot into a powder particle, homogenization heat treatment in air or in protective gas on the alloy before or shortly after its fractioning, and carrying out a diffusion treatment on the tape, thread or powder of at least one of elements comprising carbon, hydrogen and nitrogen, to obtain an alloy powder having the targeted final composition; and (3) a precursor material.

Description

technical field [0001] The present invention relates to Fe-Si-La alloys having excellent magnetocaloric properties, more particularly, but not necessarily limited to, intended for use in the manufacture of refrigeration elements. Background technique [0002] Magnetocaloric materials are magnetic materials that respond to the attractive force of an external magnetic field by changing their magnetic entropy level. This entropy change ΔS m Internally transferred to the atomic lattice of the material, this translates this into increased or decreased vibrations and thus into heating or cooling of the material. [0003] The entropy change occurs at the transition temperature T t Nearby, this temperature corresponds to the Curie temperature of ferromagnetic compounds. Under the applied field H at temperature T, by using at the transition temperature T t A network of nearby magnetization curves M(T,H) is obtained according to the resulting entropy change ΔS m : [0004] ...

AI Technical Summary

Problems solved by technology

However, arsenic is a highly toxic element to be avoided, and tantalum and hafnium are difficult to produce

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