MAGNETIC MATERIAL WITH LARGE MAGNETIC-FIELD-INDUCED DEFORMATION

• US 20090092817A1
• Filed: 09/02/2008
• Published: 04/09/2009
• Est. Priority Date: 08/30/2007
• Status: Active Grant

• Current Assignee: Boise State University, Northwestern University
• Original Assignee: Boise State University, Northwestern University
• Inventors: BOONYONGMANEERAT, YUTTANANT, DUNAND, DAVID C., CHMIELUS, MARKUS, MULLNER, PETER
• Granted Patent: US 7,964,290 B2
• Time in Patent Office: Days
• US Class Current: 428/304.4
• CPC Class Codes: C22C 19/00 Alloys based on nickel or cobalt
• CPC Class Codes: C22C 38/00 Ferrous alloys, e.g. steel alloys cast-iron alloys C22C37/00
• CPC Class Codes: H01F 1/0308 with magnetic shape memory [MSM], i.e. with lattice transformations driven by a magnetic field, e.g. Heusler alloys
• CPC Class Codes: H01F 1/408 half-metallic, i.e. having only one electronic spin direction at the Fermi level, e.g. CrO2, Heusler alloys H01F10/1936 takes precedence
• CPC Class Codes: Y10T 428/12479 Porous [e.g., foamed, spongy, cracked, etc.]
• CPC Class Codes: Y10T 428/12681 Ga-, In-, Tl- or Group VA metal-base component
• CPC Class Codes: Y10T 428/12771 Transition metal-base component
• CPC Class Codes: Y10T 428/12861 Group VIII or IB metal-base component
• CPC Class Codes: Y10T 428/12931 Co-, Fe-, or Ni-base components, alternative to each other
• CPC Class Codes: Y10T 428/12944 Ni-base component
• CPC Class Codes: Y10T 428/12951 Fe-base component
• CPC Class Codes: Y10T 428/249953 Composite having voids in a component [e.g., porous, cellular, etc.]

Abstract

A magnetic materials construct and a method to produce the construct are disclosed. The construct exhibits large magnetic-field-induced deformation through the magnetic-field-induced motion of crystallographic interfaces. The construct is a porous, polycrystalline composite structure of nodes connected by struts wherein the struts may be monocrystalline or polycrystalline. If the struts are polycrystalline, they have a “bamboo” microstructure wherein the grain boundaries traverse the entire width of the strut. The material from which the construct is made is preferably a magnetic shape memory alloy, including polycrystalline Ni—Mn—Ga. The construct is preferably an open-pore foam. The foam is preferably produced with a space-holder technique. Space holders may be dissolvable ceramics and salts including NaAlO₂.

Claims

1. A magnetic material, comprising:

a polycrystalline porous structure of the solid magnetic material;

said porous structure comprising struts connected at nodes;

said struts having twin boundaries which extend transversely across an entire strut.

2. The material of claim 1 including alloys formed from the elements Ni—

Mn—

Ga.

3. The material of claim 1 including alloys formed from the elements Fe—

Pt.

4. The material of claim 1 including alloys formed from the elements Fe—

Pd.

5. The material of claim 1 including alloys formed from the elements Ni—

Co—

Ga.

6. The material of claim 2 which comprises at least 10 atomic percent each of Ni, Mn and Ga.

7. A magnetic material, comprising:

a polycrystalline porous structure of the solid magnetic material;

said porous structure comprising polycrystalline struts connected at nodes;

said polycrystalline struts having grain boundaries which extend transversely across an entire strut.

8. The material of claim 7 including alloys formed from the elements Ni—

Mn—

Ga.

9. The material of claim 7 including alloys formed from the elements Fe—

Pt.

10. The material of claim 7 including alloys formed from the elements Fe—

Pd.

11. The material of claim 7 including alloys formed from the elements Ni—

Co—

Ga.

12. The material of claim 7 which comprises at least 10 atomic percent each of Ni, Mn and Ga.

13. A method for making a porous magnetic material which comprises infiltrating the material with a dissolvable ceramic or salt space-holder.

14. The method of claim 13 wherein the space-holder is NaAlO₂.