CAREER: Understanding the interplay of magnetism, structure and composition in high entropy alloys

University Of California-Davis, Davis CA

Investigators

Abstract

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). NON-TECHNICAL SUMMARY: High entropy alloys (HEA) are comprised of five or more elements usually in equiatomic proportions. HEA show fascinating novel properties including high temperature strength, exceptional ductility and high corrosion resistance which are currently being investigated for applications in aircrafts, cars, submarines, and buildings. Their magnetic behavior is also being considered for applications such as electric cars and aeronautics where both magnetism and mechanical strength are needed due to high speed and operating temperature requirements. However, there is a wide knowledge gap in fundamental understanding of magnetic behavior of HEA, as most of the experimental studies have concentrated on bulk magnetization measurements which cannot access nanometer lengthscales. This project focuses on understanding magnetic properties of HEA thin films and correlating it with structural behavior by carefully tuning the composition of HEA thin films. Research activities involve synthesis and characterization of HEA thin films including synchrotron-based x-ray spectroscopy and x-ray imaging techniques to characterize magnetic behavior and structural details at nanometer lengthscales. The microscopic view of HEA system developed in this project will enable material design for a wide variety of magnetic applications including electrical power generation and transmission, permanent magnets, aeronautics and consumer electronics. Education activities include introducing students to opportunities at U.S. National Laboratories and collaborating with University of California Davis Mathematics Engineering Science Achievement (MESA) and AvenueE Programs to engage community college students in science, technology, engineering, and mathematics. Annual MSE summer camp, internship program and bridge initiative will be established under this project. This project provides graduate and undergraduate students training in interdisciplinary fields at the intersection of materials science, physics, and chemistry. TECHNICAL SUMMARY: The goal of this projects is to elucidate nanoscale magnetic and structural behavior of HEA in a non-destructive and element-specific manner. Synchrotron-based x-ray spectroscopy and imaging techniques will be utilized to access material response at relevant nanometer lengthscales. Specific objectives include, (i) developing a cohesive synthesis approach for HEA thin films and characterization to explore the multicomponent phase space, (ii) evaluating the relationship between element-specific magnetic behavior and short-range ordering by using x-ray spectroscopy techniques, and (iii) examining the impact of nanoscale effects for both magnetic domain structure and microstructure by utilizing x-ray imaging techniques. The scientific knowledge established in this project will lead to development of transformative and unified understanding of magnetic and structural behavior of HEA films which will assist development of an atomistic view of HEA and their exceptional properties. Comprehensive knowledge of the relationship between magnetic and structural properties will enable theoretical prediction for tuning magnetic behavior in HEA to achieve desired functionalities and material response. Education activities include the training of undergraduate and graduate students in state-of-the art deposition and characterization tools, including synchrotron radiation-based characterization techniques at U.S. National Laboratories, and engaging students in HEA research and National Labs through development of summer camps and bridge program. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.