Domain Mechanisms in Magnetic Shape Memory Alloys

Michigan Technological University, Houghton MI

Investigators

Abstract

NONTECHNICAL SUMMARY This award supports theoretical and computational research and education that is aimed to advance fundamental understanding of domain phenomena in magnetic shape memory alloys as well as other technologically important multifunctional materials for applications in sensors, actuators, transducers, and energy harvesting. Domains are usually tiny regions inside of materials but still contain many atoms that have organized themselves in the same way, for example with the same structure or same magnetic orientation, but are organized differently in neighboring domains. Physical processes involving domains are responsible for the properties of these materials that make them useful for a particular application, their functionality. The PI will combine complementary domain-level computational and experimental approaches to investigate domain phenomena in complex magnetic materials with an aim to establish connections between materials properties and domain processes. The research will provide training for a graduate student in materials science, and creates research opportunities and experiences for undergraduates. The research outcomes provide valuable real-world inspired examples for teaching computational materials science and physical behaviors of materials in courses. The PI will participate in existing outreach activities at Michigan Technological University to promote materials science and engineering among high school students, women and underrepresented minorities. TECHNICAL SUMMARY This award supports theoretical and computational research and education that is aimed to advance fundamental understanding of domain phenomena in magnetic shape memory alloys and other technologically important multifunctional materials. Magnetic shape memory alloys actively respond to external magnetic, mechanical, and thermal stimuli, and are capable of energy conversion. Magnetic shape memory alloy functionalities originate from the evolution of coupled magnetic and elastic domain microstructures, which leads to rich domain phenomena and sophisticated physical behaviors that are important for both basic science and technological applications. The PI seeks to establish correlations between macroscopic properties and internal domain processes, identify underlying domain mechanisms, and find effective ways to optimize the domain microstructures and control their evolution pathways to tailor the useful properties. This project involves the quantitative investigation of coupled magnetic and elastic domain processes to address important domain mechanisms by domain-level modeling and simulations using phase-field micromagnetic microelastic methods and in-situ domain observation experiments using an interference-contrast-colloid technique. In particular, the PI will focus on the effects of (i) magnetostriction, (ii) twin boundary mobility, (iii) magnetic easy direction, and (iv) nanoscale structural heterogeneity on domain processes and the resultant field-induced deformation behaviors. These effects determine magnetoelastic properties, but their roles are yet to be clarified. The objectives of the research are to: (1) develop computational tools to perform realistic simulation studies of domain microstructure evolutions; (2) carry out coordinated in-situ domain observation experiments; (3) identify important domain mechanisms governing magnetoelastic behaviors; (4) advance fundamental understanding of domain processes and provide insight into property improvement and guidance for new materials development; and (5) integrate the research into the PI's educational and outreach activities in functional materials and computational materials science.