ISSN 1061-3862, International Journal of Self-Propagating High-Temperature Synthesis, 2009, Vol. 18, No. 3, pp. 207–212. © Allerton Press, Inc., 2009. 207 1 INTRODUCTION Magnetostrictive materials are distinguished by the phenomenon of dimensional changes occurring in applied magnetic field. This change in length is the out- come of the rotation of magnetic domains. In the case of positive magnetostriction, the domain rotation causes internal strains through the material structure which lead to the stretching of the material in the direc- tion of the magnetic field [1]. Clark et al. have shown that the magnetostriction effect of α-Fe body-centered cubic (bcc) structure increases significantly upon addi- tion of non-magnetic Ga atoms [2–5]. Substitution of Fe with ~19% of Ga in single crystal (named galfenol) exhibits up to 400 ppm (10 times more than bcc α-Fe) magnetostrictive strains along the [100] crystallo- graphic direction. In addition to their high magneto- striction effect, these alloys are mechanically strong with tensile strengths up to 500 MPa and can be rolled, extruded, and welded. These properties make galfenol well suited for use in a number of technologies includ- ing micro acoustic sensors, generators, marine sonar devices, linear motors, robust actuators, and position- ing devices. While single crystals of galfenol alloys can provide large magnetostriction, fabrication of single crystals is 1 The article is published in the original. still a time-consuming and expensive process. Thus, development of textured polycrystalline galfenol using relatively low-cost fabrication procedures is an impor- tant technological problem. Polycrystalline Fe 85 Ga 15 galfenol alloys prepared by different techniques usually exhibit magnetostriction of up to about 200 ppm. The texturing, or preferential orientation of the crystallo- graphic structure in metals and intermetallics, has been used to tailor their physical and mechanical character- istics. As proposed in [6–8], the special micro-textured morphology of galfenol can significantly increase the magnetostriction effect. Mechanochemical synthesis of particulate solids using high-energy milling has been used as a powerful tool for the preparation of metastable crystalline and amorphous phases and nanostructured materials not obtainable through conventional methods [9–11]. Mechanical treatment increases the reactivity of the solid reactants, through the generation of extended crystal defects, new surfaces, and lattice distortions, thus facilitating the occurrence of transformations in the solid state. This leads to shortening the reaction time and in some cases reduces a temperature usually required for developing solid state reactions and the possibility of obtaining materials with special proper- ties. Fabrication and Magnetic Properties of Submicro-Textured Magnetostrictive Alloys 1 K. S. Martirosyan a , E. Galstyan b , and D. Litvinov a, c a Department of Chemical and Biomolecular Engineering, University of Houston, 4800 Calhoun, Houston, Texas, 77204 USA b Texas Center for Superconductivity, University of Houston, 4800 Calhoun, Houston, Texas, 77204 USA c Department of Electrical and Computer Engineering, University of Houston, 4800 Calhoun, Houston, Texas, 77204 USA e-mail: kmartirossian@uh.edu Received May 21, 2009 Abstract—A novel method for fabrication of submicro-textured magnetostrictive alloys (Fe 85 Ga 15 ) by using mechanochemical treatment of iron and gallium reactants followed high-temperature sintering is reported. To reduce the surface tension and enhance the chemical reaction between iron and gallium up to 1% of surfactant (oleic acid) was used during the mechanochemical synthesis of Fe 85 Ga 15 particles. The sintered sample was processed using a flat-roll machine to obtain 100 μm thick ribbons at room temperature. The ribbons were annealed at 600°C in argon and slowly cooled down for over 3 h. SEM analysis of the ribbons shows a submi- cron structure of the fabricated alloys. XRD data for annealed ribbons confirm a long-range ordering of Ga atoms into a DO 3 structure. The magnetization plot M(H) at 5 and 280 K of the Fe 85 Ga 15 ribbon did not display a visible magnetic hysteresis loop and exhibited a very low coercivity of H c = 4.7 and 1.9 Oe and remnant moment of M rem = 0.28 and 0.1 emu/g, respectively, with a saturation magnetization of about 162 emu/g. A larg- est magnetostriction up to 220 ppm was measured along the ribbon length in a perpendicular magnetic field. Keywords: mechanochemical synthesis, magnetostrictive alloys, galfenol, magnetization PACS numbers: 75.50.y, 81.20.Ev, 81.20.Ka DOI: 10.3103/S1061386209030121