Technical and Scientific Impact Improved understanding of magnetostriction developed.

Strong, Ductile and Low-Field Magnetostrictive Alloys Based on Fe-GaStrong, Ductile and Low-Field Magnetostrictive Alloys Based on Fe-Ga

PPI:I: Sivaraman Guruswamy, University of Utah Sivaraman Guruswamy, University of Utah MET MET DMR Award # DMR Award # 02416030241603


PPI:I: Sivaraman Guruswamy, University of Utah Sivaraman Guruswamy, University of Utah MET MET DMR Award # DMR Award # 02416030241603

Technical and Scientific Impact

• Improved understanding of magnetostriction developed.

• The laboratory selected as a 2005 State of Utah Center of Excellence in Magnetic Sensor and Actuator Materials Stoel Rieves Innovation award finalist, Salt Lake City, 2006

• FeGa alloys being considered for numerous sensor and actuator applications such as sonic and ultrasonic devices, nanovalves, load sensors, ABS, and active damping devices

Significant Findings

• Large substitutions of Ga with Al and Be can be made in Fe-20 at% Ga alloys while retaining large magneto-striction. Optimal FeGaAl compositions identified.

• A safe technique for preparing FeBe alloys was developed.

• Inexpensive and simple large scale thermomechanical processing method developed for obtaining polycrystalline Fe-15 at.% Ga alloys with desired strong [001] texture.

• The effect of solute additions on the magnetostriction of Fe arises mainly from changes in local atomic environment, and the effect due to image stresses is less significant.

• Formation of all LRO ordered phases can be avoided through careful process control. Addition of Al can be used to suppress the L12 and DO19 ordering in FeGa alloys.

Research Focus

• Magnetostriction refers to the change in the length of a material when a magnetic field is applied. Ga addition dramatically increases the magnetostriction of Fe. FeGa based alloys with attractive combinations of low hysteresis, low saturation field, good mechanical properties, and low cost developed for use in sensor and actuators applications

• Research focuses on developing a fundamental understanding needed to develop other low cost Fe based magnetostrictive alloys, and low cost processing methods.

Pole figure showing

strong [100] texture

developed through

TMP in Fe-15 at.%

Ga alloy

Large magnetostriction in Directionally Grown Fe-27.5 at.% Ga alloy

0

100

200

300

-800 -400 0 400 800

H (Oe)

Mag

neto

stri

ctio

n (p

pm) (a)

[200] lattice image from Fe-27.5 at.% Ga alloy after a ” ordering

[110] Electron

diffraction pattern

of ” ordered Fe-

27.5 at.% Ga. Applications


PI:PI: Sivaraman Guruswamy, University of Utah Sivaraman Guruswamy, University of Utah

MET DMR Award # MET DMR Award # 02416030241603




Over 18 invited and contributed presentations, 5 Journal papers (3 in print and 2 in review), 15 Proceedings papers, 2 PhD dissertations, and 1 MS thesis

Education and Training

Seven graduate students (Four PhD and 3 MS degree) and three undergraduates have been supported. Five have presented papers in the national meetings.

All students are trained in advanced processing and characterization techniques including single crystal growth, OIM in SEM, TEM, XRD, magnetic and magnetostriction measurements, and Resonant Ultrasound Spectroscopy

Students built nanopositioning and ultrasonic device prototypes Undergraduate student Rebecca Chandler presented a poster

paper on “The influence of ordering on magnetostriction” at the Univ. of Utah Undergraduate Research Conference and was a co-author of the paper presented at the TMS Annual Meeting

Students in Physical Metallurgy, Magnetic Materials, and Materials Design classes exposed to MML and ongoing research Outreach Activities

Robert Corson was selected as a member of the US student delegation to the 54th Annual Meeting of Students with the Nobel Laureates in Lindau Germany, held during June-July 2004

The PI and the graduate students showcased the Magnetic Materials Laboratory to well over 250 high school students, middle school students, and parents during the Science days, Open-houses, and other arranged and informal visits

Technological Innovation Showcase meetings in 2003, 2004,2005 and 2006 in Salt Lake City, and State Technology Showcase in 2005. Open to public.

Over 18 presentations, 18 Journal/conference papers, 2 PhD and 1 MS publications

Robert Corson attending the 54th Annual Meeting of Students with the Nobel Laureates in Lindau Germany, during June-July 2004

Rebecca Chandler presenting a poster at the Undergraduate Research Conference

High School Students and parents watching the demonstration of a magnetostrictive ultrasonic device

Middle school students from Youth Teaching Youth program with Prof. Guruswamy outside MML clean room

Graduate studens Swieng and under-graduate Gavin testing a single crystal growth system

Graduate student Pinai helping undergraduate Rebecca Chandler with magnetic measurements using a VSM

Fe-Zn and other binary iron alloys are being studied to gain improved understanding of magnetsotriction and develop new low cost alloys. Powder metallurgy processing involving explosive compaction is used here to obtain full density FeZn alloys. Figure on the right shows an x-ray tomography image of a section in an as-explosively compacted Fe-Zn sample prepared for magnetostriction studies. The image is 5.4 x 4.5 mm in Size. Full density regions as well as regions with cracks and central porosity resulting from high compaction pressures can be seen.







Fe-Ga alloys show the highest values of magnetostriction in disordered bcc form. Magnetostriction decreased slightly on extended ordering treatment in ” range. DO19 and L12,

ordering decrease magnetostriction to nearly

zero or a small negative value. The figure on the left shows a [200] lattice image from Fe-27.5 at.% Ga alloy after a ” ordering. The figure on the right shows [110] electron diffraction pattern for ” ordered Fe-27.5 at.% Ga

Zn K X-ray map of Fe-30 at.%

Zn alloy (a) before and (b) after homogenization anneal

(a)

(b)

X-ray tomography image of a section from an explosively compacted Fe-Zn sample

Technical and Scientific Impact Improved understanding of magnetostriction developed.

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