Recent developments in Ni-Mn-Ga foam research

Peter Müllner*, Xuexi Zhang, Yuttanant Boonyongmaneerat, Cassie Witherspoon, Markus Chmielus, David C. Dunand

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Scopus citations

Abstract

Grain boundaries hinder twin boundary motion in magnetic shape-memory alloys and suppress magnetic-field-induced deformation in randomly textured polycrystalline material. The quest for high-quality single crystals and the associated costs are a major barrier for the commercialization of magnetic shape-memory alloys. Adding porosity to polycrystalline magneticshape memory alloys presents solutions for (i) the elimination of grain boundaries via the separation of neighboring grains by pores, and (ii) the reduction of production cost via replacing the directional solidification crystal growth process by conventional casting. Ni-Mn-Ga foams were produced with varying pore architecture and pore fractions. Thermo-magnetic training procedures were applied to improve magnetic-field-induced strain. The cyclic strain was measured in-situ while the sample was heated and cooled through the martensitic transformation. The magnetic field-induced strain amounts to several percent in the martensite phase, decreases continuously during the transformation upon heating, and vanishes in the austenite phase. Upon cooling, cyclic strain appears below the martensite start temperature and reaches a value larger than the initial strain in the martensite phase, thereby confirming a training effect. For Ni-Mn-Ga single crystals, external constraints imposed by gripping the crystal limit lifetime and/or magnetic-field-induced deformation. These constraints are relaxed for foams.

Original languageEnglish (US)
Title of host publicationFerromagnetic Shape Memory Alloys II
PublisherTrans Tech Publications Ltd
Pages119-124
Number of pages6
ISBN (Print)087849295X, 9780878492954
DOIs
StatePublished - 2010
Event2nd International Conference on Ferromagnetic Shape Memory Alloys, ICFSMA2009 - Bilbao, Spain
Duration: Jul 1 2009Jul 3 2009

Publication series

NameMaterials Science Forum
Volume635
ISSN (Print)0255-5476
ISSN (Electronic)1662-9752

Other

Other2nd International Conference on Ferromagnetic Shape Memory Alloys, ICFSMA2009
CountrySpain
CityBilbao
Period7/1/097/3/09

Keywords

  • Cast structure
  • Fatigue
  • Foam
  • Large strain
  • Polycrystalline

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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