The fabrication and analysis of the magnetic and crystallographic properties of Fe-rich (Fe x Ga 1-x) Galfenol alloys

• Main Author: Quinn, C. J.
• Published: University of Salford 2012
• Subjects: 620.1; Energy
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.575064

Understanding the fundamental physics and properties of smart materials is a very important area of research for nano and micro mechanical systems especially in the applications of sensing and actuation, such as SONAR. This thesis is focused on the investigations of Galfenol solid solutions and the associated magnetic properties, crystal structures and the influence that additional Ga has upon a Fe-rich Galfenol system. This has been achieved by using a variety of compositions of Fe1-xGax melt-spun alloy ribbons and then characterised using a number of measurement techniques including; x-ray diffraction, neutron diffraction, Mössbauer interaction, differential scanning calorimetry, vibrating sample magnetometry and electron microscopy. By identifying the various crystallographic phases and their relevant magnetic properties a clearer picture has been established to enable further research to build upon the results published in this thesis. After fabrication several standard measurements were taken to evaluate the crystalline phases within and the proposed site occupancy of the atomic structure. Compositional analysis was performed in order to clarify the specific atomic weight percentages produced. Magnetic and thermal magnetic measurements were then undertaken to measure magnetic saturation values and relevant Curie temperatures. Further thermal measurements were taken in order to explain some of the anomalous thermo-magnetic results in the two most dilute compositions. These results were directly compared to ascertain both the structural and magnetic changes that were instigated by the thermal treatment of the alloys. Finally, some rapid annealing and quenching and also a slow cooling treatment was applied to the most dilute composition in order to capture the structural transformation caused by the thermal treatment and these resulting phases identified and the results discussed.