“Bridging Length Scales in Deforming Single and Textured Polycrystals of Structural Magnetic Shape Memory Alloys (MSMAs)”

I. Karaman and D. C. Lagoudas, Texas A&M University, DMR- 0244126Motivation

•Engineer the compositions and microstructure of selected FeNiCo and CoNi(Al,Ga) alloys to obtain MSMAs with high saturation magnetization and magnetocrystalline anisotropy energy.•Investigate magneto-thermo-mechanical behavior of selected MSMAs in single and textured polycrystalline forms to reveal the governing mechanisms. •Fabricate textured polycrystals utilizing consolidation under magnetic field•Develop a thermodynamically sound model that will consider hysteresis effects, texture and the coupling temperature, stress and magnetic field effects on MSM.

Tools

300

250

200

150

100

50

0

Str

ess,

MP

a

3.02.52.01.51.00.50.0Strain,%

CoNiAl compression<100> direction

145°C 160°C 170°C

5

4

3

2

1

0

Str

ain,

%

-15x103

-10 -5 0 5 10 15Magnetic Field,G

2 MPa 3 MPa 4 MPa 5 MPa 6 MPa

Ni2MnGa

Experimental Results

•Constitutive model based on Gibbs free energy expression which includes magnetic energy terms and dissipative effects introduced through internal state variables, which are physically motivated by magnetic and crystallographic microstructure

•Numerical predictions of reorientation strain-magnetic field-hysteresis curves for different applied stress values in NiMnGa

Development of compositions that resulted in wide temperature range in which pseudoelasticity observed (-100 C to 200 C), high strength and up to 5 % recoverable shape change, very low thermal and stress hysteresis as compared to NiTi, and magnetic field induced strain as high as 5%.

Modeling Results

Powder consolidation using Equal Channel Angular Extrusion under magnetic field

In-house built magneto thermo mechanical testing set-up

“Bridging Length Scales in Deforming Single and Textured Polycrystals of Structural Magnetic Shape Memory Alloys (MSMAs)”

I. Karaman and D. C. Lagoudas, Texas A&M University, DMR- 0244126Broad Impact

•Publication of four manuscripts (Scripta Materialia,Vol. 51, 261-266 (2004), Scripta Materialia, Vol. 49, 831-838 (2003), one submitted to Philosophical Magazine A, Smart Structures and Materials 2004 Conference Proceedings).•Collaboration with Prof. Hans J. Maier of University of Paderborn, Germany and Prof. Yuriy I. Chumlyakov and Dr. I. Kireeva of Siberian Physical-Technical Institute, Russia. Mutual visits between collaborators. •Collaboration with Dr. Yang Ren of Advanced Photon Source, Argonne National Laboratory. One graduate and one undergraduate student will visit ANL in November.• Undergraduate student exchange program between University of Paderborn (UP), Germany and Texas A&M University.

Education• Three graduate (one female) and six undergraduate (two female, one asian-american) students were involved in this work.

• One of the undergraduate students (Joseph Mather) is currently a PhD student at UIUC. A conference paper is presented together with undergraduate students•Two graduate students attended international conferences and one visited UP to work with German graduate students• Close collaboration with Harmony Science Academy (HSA) (K-12 charter school with 60% hispanic and 20% African-American student body).•Five middle and high school students (two female, two hispanic, one african-american, one asian-american) prepared science projects and got several awards.•Shape memory alloys have been incorporated into an art class by Ms. Alcorn of HSA.

Taylor Towns (K-9) conducting experiments on Smart Springs

Alexander Galit (K-9) is with his poster on “Smart Materials Never Forget”

Tiffany Tiemann (junior UG) is conducting DSC experiments on CoNiGa alloys

Collaboration with High Schools

Collaboration with High Schools SCIENCE AND ENGINEERING FAIR OF HOUSTON 2004

Name School Project Title Category Awarding Agency Rank Supervisor

Malhissa Reyes

Harmony Science Academy

Shape Memory Alloys

Junior-Engineering

American Society for Materials 2nd Dr. Ibrahim Karaman

Alexander Galit

Harmony Science Academy

Smart Materials Never Forget

9th – Engineering

American Society of Materials 1stDr. IbrahimKaraman

Marnesar Javier

Harmony Science Academy

Smart Springs 9th-EngineeringTexas Society of Professional Engineers

1stDr. Ibrahim Karaman

Marnesar Javier

Harmony Science Academy

Smart Springs 9th-EngineeringAmerican Society of Indian Engineers

1stDr. Ibrahim Karaman

Marnesar Javier

Harmony Science Academy

Smart Springs 9th-Engineering M.I.T. Club of South texas 1stDr. Ibrahim Karaman

Marnesar Javier

Harmony Science Academy

Smart Springs 9th-EngineeringUniversity of Houston Engineering Alumni Association

1stDr. Ibrahim Karaman

Nathan Colbert

Harmony Science Academy

Liquid Metals Junior-Engineering

American Society for Materials 1stDr. Ibrahim Karaman

TEXAS JUNIOR ACADEMY OF SCIENCE 2004 (at Texas A&M)

Name School Project Title Category Rank Supervisor

Marnesar Javier

Harmony Science Academy

Smart Springs Engineering Honorable MentionDr. Ibrahim Karaman

AUSTIN REGIONAL SCIENCE FAIR

Name School Project Title Category Rank Supervisor

Taylor Towns

Austin Science Academy

Smart Springs Engineering 4th PlaceDr. Ibrahim Karaman

“Bridging Length Scales in Deforming Single and Textured Polycrystals of Structural Magnetic Shape Memory Alloys (MSMAs)”

I. Karaman and D. C. Lagoudas, Texas A&M University, DMR- 0244126