Alloy and method for producing magnetic refrigeration material particles using same

1. An alloy comprising La in a range of 4 to 15 atomic %, Fe in a range of 60 to 93 atomic %, Si in a range of 3.5 to 23.5 atomic % and at least one element M selected from B and Ti in a range of 0.5 to 1.5 atomic %,

wherein the alloy comprises 55 volume % or more of a main phase which comprises α-Fe phase comprising Si, and a subphase which comprises intermetallic compound phase comprising La as a main component element and Si, and the main phase has a bcc crystal structure and an average grain diameter of 20 μm or less.

2. The alloy according to claim 1 ,

wherein the Fe is partially replaced by at least one element selected from Co, Ni and Mn.

3. The alloy according to claim 2 ,

wherein the alloy comprises Co in 10 atomic % or less.

4. The alloy according to claim 1 ,

wherein the La is partially replaced by at least one element selected from Ce, Pr and Nd.

5. The alloy according to claim 1 ,

wherein the alloy comprises La in a range of 6 to 12 atomic %.

6. The alloy according to claim 1 ,

wherein the alloy comprises Fe in a range of 75 to 90 atomic %.

7. The alloy according to claim 1 ,

wherein the alloy comprises Si is contained in a range of 4 to 15 atomic %.

8. The alloy according to claim 1 ,

wherein the alloy comprises element M in a range of 0.9 to 1.2 atomic %.

9. The alloy according to claim 1 ,

wherein the alloy has a cylindrical shape.

10. The alloy according to claim 1 ,

wherein the alloy has a cylindrical shape having a diameter of 10 mm or more and a length of 100 mm or more.

11. A method for producing magnetic refrigeration material particles, comprising:

melting partially with a plasma a cylindrical alloy material which comprises La in a range of 4 to 15 atomic %, Fe in a range of 60 to 93 atomic %, Si in a range of 3.5 to 23.5 atomic % and at least one element M selected from B and Ti in a range of 0.5 to 1.5 atomic %, while rotating the cylindrical alloy materials;

separating the melted alloy into small pieces in a molten state by centrifugal force;

spheroidizing the melted alloy separated into the small pieces by the surface tension in an atmosphere;

solidifying the spheroidized small pieces in an atmosphere; and

heat-treating the solidified small pieces to generate a La(Fe, Si) 13 phase,

wherein the cylindrical alloy material comprises 55 volume % or more of a main phase which comprises α-Fe phase comprising Si, and a subphase which comprises intermetallic compound phase comprising La as a main component element and Si, and the main phase has a bcc crystal structure and an average grain diameter of 20 μm or less.

12. The method according to claim 11 ,

wherein the solidified small pieces are subjected to the heat treatment under conditions of a temperature of 900 to 1100° C. for 12 to 240 hours.

13. The method according to claim 11 ,

wherein the cylindrical alloy material has a diameter of 10 mm or more and a length of 100 mm or more.

14. The method according to claim 11 ,

wherein the solidified small pieces comprise spherical particles having a diameter in a range of 0.3 to 1.2 mm.

15. The method according to claim 11 ,

wherein the Fe is partially replaced by at least one element selected from Co, Ni and Mn.

16. The method according to claim 15 ,

wherein the alloy material comprises Co in a range of 10 atomic % or less with respect to the whole alloy composition.

17. The method according to claim 11 ,

wherein the La is partially replaced by at least one element selected from Ce, Pr and Nd.