Effect of pore architecture on magnetic-field-induced strain in polycrystalline Ni-Mn-Ga

X. X. Zhang; C. Witherspoon; P. Müllner; D. C. Dunand

doi:10.1016/j.actamat.2010.12.026

Effect of pore architecture on magnetic-field-induced strain in polycrystalline Ni-Mn-Ga

X. X. Zhang, C. Witherspoon, P. Müllner, D. C. Dunand

Materials Science and Engineering

Research output: Contribution to journal › Article › peer-review

39 Scopus citations

Abstract

Monocrystalline Ni-Mn-Ga alloys show magnetic-field-induced strains (MFIS) of up to 10% as a result of reversible twinning; by contrast, polycrystalline Ni-Mn-Ga shows near-zero MFIS due to strain incompatibilities at grain boundaries inhibiting twinning. Recently, we showed that porous polycrystalline Ni-Mn-Ga exhibits a small, but non-zero, MFIS value of 0.12% due to reduction of these incompatibilities by the porosity. Here, we study the effect of pore architecture on MFIS for polycrystalline Ni-Mn-Ga foams. Foams with a combination of large (∼550 μm) and small (∼80 μm) pores are fabricated by the replication method and exhibit thinner nodes and struts compared to foam containing only large (∼430 μm) pores. When magnetically cycled, both types of foams exhibit repeatable MFIS of 0.24-0.28% without bias stress. As the cycle number increases from a few tens to a few thousands, the MFIS drops due to damage accumulation. The rate of MFIS decrease is lower in the dual-pore foam, as expected from reduced constraints on the twin boundary motion, since twins span the whole width of the thinner nodes and struts.

Original language	English (US)
Pages (from-to)	2229-2239
Number of pages	11
Journal	Acta Materialia
Volume	59
Issue number	5
DOIs	https://doi.org/10.1016/j.actamat.2010.12.026
State	Published - Mar 2011

Funding

The authors thank Mr. Adrian Rothenbühler and Dr. Markus Chmielus (both at Boise State University) for assistance with magnetic and magneto-mechanical experiments. This project was funded by the National Science Foundation through Grants NSF-DMR 0804984 (Boise State University) and DMR-805064 (Northwestern University). P.M. is thankful to ETH Zürich for donating magneto-mechanical testing devices.

Keywords

Casting
Magnetostriction
NiMnGa
Nickel alloys
Porous material

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Ceramics and Composites
Polymers and Plastics
Metals and Alloys

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10.1016/j.actamat.2010.12.026

Cite this

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title = "Effect of pore architecture on magnetic-field-induced strain in polycrystalline Ni-Mn-Ga",

abstract = "Monocrystalline Ni-Mn-Ga alloys show magnetic-field-induced strains (MFIS) of up to 10% as a result of reversible twinning; by contrast, polycrystalline Ni-Mn-Ga shows near-zero MFIS due to strain incompatibilities at grain boundaries inhibiting twinning. Recently, we showed that porous polycrystalline Ni-Mn-Ga exhibits a small, but non-zero, MFIS value of 0.12% due to reduction of these incompatibilities by the porosity. Here, we study the effect of pore architecture on MFIS for polycrystalline Ni-Mn-Ga foams. Foams with a combination of large (∼550 μm) and small (∼80 μm) pores are fabricated by the replication method and exhibit thinner nodes and struts compared to foam containing only large (∼430 μm) pores. When magnetically cycled, both types of foams exhibit repeatable MFIS of 0.24-0.28% without bias stress. As the cycle number increases from a few tens to a few thousands, the MFIS drops due to damage accumulation. The rate of MFIS decrease is lower in the dual-pore foam, as expected from reduced constraints on the twin boundary motion, since twins span the whole width of the thinner nodes and struts.",

keywords = "Casting, Magnetostriction, NiMnGa, Nickel alloys, Porous material",

author = "Zhang, {X. X.} and C. Witherspoon and P. M{\"u}llner and Dunand, {D. C.}",

note = "Funding Information: The authors thank Mr. Adrian Rothenb{\"u}hler and Dr. Markus Chmielus (both at Boise State University) for assistance with magnetic and magneto-mechanical experiments. This project was funded by the National Science Foundation through Grants NSF-DMR 0804984 (Boise State University) and DMR-805064 (Northwestern University). P.M. is thankful to ETH Z{\"u}rich for donating magneto-mechanical testing devices.",

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AU - Müllner, P.

AU - Dunand, D. C.

N1 - Funding Information: The authors thank Mr. Adrian Rothenbühler and Dr. Markus Chmielus (both at Boise State University) for assistance with magnetic and magneto-mechanical experiments. This project was funded by the National Science Foundation through Grants NSF-DMR 0804984 (Boise State University) and DMR-805064 (Northwestern University). P.M. is thankful to ETH Zürich for donating magneto-mechanical testing devices.

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N2 - Monocrystalline Ni-Mn-Ga alloys show magnetic-field-induced strains (MFIS) of up to 10% as a result of reversible twinning; by contrast, polycrystalline Ni-Mn-Ga shows near-zero MFIS due to strain incompatibilities at grain boundaries inhibiting twinning. Recently, we showed that porous polycrystalline Ni-Mn-Ga exhibits a small, but non-zero, MFIS value of 0.12% due to reduction of these incompatibilities by the porosity. Here, we study the effect of pore architecture on MFIS for polycrystalline Ni-Mn-Ga foams. Foams with a combination of large (∼550 μm) and small (∼80 μm) pores are fabricated by the replication method and exhibit thinner nodes and struts compared to foam containing only large (∼430 μm) pores. When magnetically cycled, both types of foams exhibit repeatable MFIS of 0.24-0.28% without bias stress. As the cycle number increases from a few tens to a few thousands, the MFIS drops due to damage accumulation. The rate of MFIS decrease is lower in the dual-pore foam, as expected from reduced constraints on the twin boundary motion, since twins span the whole width of the thinner nodes and struts.

AB - Monocrystalline Ni-Mn-Ga alloys show magnetic-field-induced strains (MFIS) of up to 10% as a result of reversible twinning; by contrast, polycrystalline Ni-Mn-Ga shows near-zero MFIS due to strain incompatibilities at grain boundaries inhibiting twinning. Recently, we showed that porous polycrystalline Ni-Mn-Ga exhibits a small, but non-zero, MFIS value of 0.12% due to reduction of these incompatibilities by the porosity. Here, we study the effect of pore architecture on MFIS for polycrystalline Ni-Mn-Ga foams. Foams with a combination of large (∼550 μm) and small (∼80 μm) pores are fabricated by the replication method and exhibit thinner nodes and struts compared to foam containing only large (∼430 μm) pores. When magnetically cycled, both types of foams exhibit repeatable MFIS of 0.24-0.28% without bias stress. As the cycle number increases from a few tens to a few thousands, the MFIS drops due to damage accumulation. The rate of MFIS decrease is lower in the dual-pore foam, as expected from reduced constraints on the twin boundary motion, since twins span the whole width of the thinner nodes and struts.

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Effect of pore architecture on magnetic-field-induced strain in polycrystalline Ni-Mn-Ga

Abstract

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Keywords

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