Project TitleMagnetic Shape-Memory Foam With Large Magnetic-Field-Induced Deformation
Track Code2007-050
Short Description

Polycrystalline Ni-Mn-Ga foam magnetic shape-memory alloys exhibiting significant reversible magnetic field-induced strain.

#materials #manufacturing #MEMS #actuator


Northwestern researchers have developed a polycrystalline Ni-Mn-Ga foam magnetic shape-memory alloy exhibiting magnetically induced strain about 50 times larger than reported for nonporous, fine-grained Ni-Mn-Ga materials.  While magnetic shape-memory alloys enable rapid, large-strain actuation upon the application of a magnetic field, there are a number of limitations to large magnetoplastic strains.  The growth of Ni-Mn0Ga single crystals is slow and leads to several segregation which affects local composition, crystal structure and magnetoplastic strain.  This invention overcomes these constraints by creating foam structures with pores that significantly reduce internal crystal constraints to dislocation, in the presence of a magnetic field.  The foam structures are comparable in strain and response time to leading nonmagnetoplastic magnetorestrictive materials such as Terfenol D, which requires a bias stress for full strain potential, and contains the more expensive Tb and Dy metals.


TagsMATERIALS: manufacturing, MEMS: actuator
Posted DateJul 4, 2011 2:06 PM


Yuttanant Boonyongmaneerat

David Dunand*

Peter Mullner

Markus Chmielus


Sensors, actuators, transducers, heat-transfer agent for magnetic refrigeration, magnetic displacement of fluids and new composite materials


  • Shape-memory
  • Significantly higher magnetoplastic strain
  • Use of foam structures to diminish internal crystal constraints to dislocation
  • Less expensive than leading nonmagnetoplastic magnetorestrictive materials
  • Magnetically induced strain about 50 times larger than reported for nonporous, fine-grained Ni-Mn-Ga materials.


IP Status

Issued US Patent No. 7,964,290

Contact Information

Arjan Quist, PhD
Invention Manager
(p) (847) 467-0305