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

Abstract

The invention relates to a Fe-Si-La alloy having the following atomic composition: (La1-a-a'MmaTRa')1[(Fe1-b-b,CobMb,)1- x(Si1-cXc)x]13(CdNeH1-d-e)y(R)z(l)f, in which Mm is a mixture of lanthanum, cerium, neodymium and praseodymium in a weight proportion of 22 to 26% of La, 48 to 53% of Ce, 17 to 20% of Nd and 5 to 7% of Pr, wherein said mixture may include up to 1 wt % of impurities, TR is one or more elements of the rare earth family other than lanthanum, M is one or more d-type transition element from layers 3d, 4d and 5d, X is a metalloid element selected from Ge, Al, B, Ga and In, R is one or more element selected from Al, Ca, Mg, K and Na, I is one or two elements selected from O and S, with: 0 <= a < 0.5 and 0 <= a' < 0.2; 0 <= b <= 0.2 and 0 <= b' < 0.4; 0 <= c <= 0.5 and 0 <= d <= 1; 0 <= e <= 1 and f <= 0.1; 0.09 <= x <= 0.13 and 0.002 <= y <= 4; 0.0001 <= z <= 0.01; the indicia b, d, e, x and y being such that the alloy further meets the following condition: 6.143b(13(1-x))+ 4.437y[1 - 0,0614(d + e)] >= 1 Eq.1 d * y >= 0.005 Eq.2. The invention also relates to a powder of this alloy or mixture of these alloys, and to a method for producing the same.

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] ...

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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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