Magnetic material with large magnetic-field-induced deformation
View Patent ↗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 NaAlO 2 .
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.