Research Focus

1. Structure–Composition-Magnetostriction Correlations in Strong and Ductile Fe-Based Alloys with Large Low-Field MagnetostrictionSivaraman Guruswamy, University of Utah, DMR 0854166 • Research Focus • Magnetostriction refers to the change in the length of a material with applied magnetic field (See figure on the right) • Magnetostrictive materials are used in numerous sensors and actuator applications: sonar, nano-positioning, load sensors, ABS, active damping, … • Research examines how local atomic environment, crystalline structure and crystal defects influence the magnetostriction in a-Fe based alloys. Figure (top right) shows Extended X-ray Absorption Fine Spectrum (EXAFS)* data (R) as a function of R and the fit obtained at the Fe K edge from long-term annealed and quenched (LTA) Fe-27.5 at.% Ga single crystal. EXAFS data obtained at the Fe K and Ga K edges for Fe-27.5 at.% Ga single crystal using Advanced Photon Source at ANL and their ongoing analysis suggest that LTA sample shows longer Ga-Ga nearest neighbor distances compared to as-grown and ordered alloy. The data also suggest local distortions in all cases. • Significant Findings • Controlling inhomogeneous elastic strains introduced by modifying local atomic spacing by solutes and defects, is key to controlling magnetostriction. • W additions of up to 4.4 at. % to Fe leads to rapid increase in magnetostriction and a slower increase above 4.4% due to the propensity to form second phase regions Technical and Scientific Impact This is a significant contribution to a fundamental understanding of magnetostriction and towards alloy design for sensor and actuators (as well as low-/zero-expansion alloys and magnetic data storage devices where we need to control this behavior). Slip patterns on sample surface Controlled introduction of dislocations is shown to lead to a decrease in magnetostriction.n

2. Structure–Composition-Magnetostriction Correlations in Strong and Ductile Fe-Based Alloys with Large Low-Field Magnetostriction Sivaraman Guruswamy, University of Utah, DMR 0854166 • Education, Training and Outreach • Graduate students Gavin Garside, Biswadeep Saha, Chai Ren and M. Ramanathan have been given research training on the project and are beginning to contribute to the goals of the project • Students have been trained in alloy synthesis, single crystal growth, XRD, magnetic measurements, SEM, and EXAFS data analysis • Gavin Garside attended the 2009 Neutron and X-ray Scattering School at ORNL/ ANL, and 2010 EXAFS workshop. Presented a paper at TMS 2010 • Showcased the lab and research during Science day 2008 and 2009, Dept. Open House (2009 and 2010) and ASM Open House (2009 and 2010) to high school students, visitors and general public. Graduate student Gavin Garside explaining the magnetic materials applications to high school students Graduate students Biswa-deep and M.Ramanathan preparing the alloy by arc- melting prior to single crystal growth • Recognitions • PI recognized with 2010 Univ. of Utah Distinguished Teaching Award and 2010 Associated Students of Univ. of Utah (ASUU) Student Choice Award • Honorable mention, Utah Innovation Awards, 2009. • PI led the successful ABET Accreditation of the Dept. in 2010 and Graduate Program Review in 2010 • Finalist in the ARPA E competition for wave energy harvesting using magnetostrictive Fe alloys Graduate students Gavin, Chai and Biswadeep trained in the use of Vibrating Sample Magnetometer system PI showcasing the Lab and research to visitors during 2010 ASM Utah Chapter open house