IRES: US-Australia Collaboration on New High Strength, High Ductility Classes of High Entropy Alloys through Intermetallic Manipulation

Harvey Mudd College, Claremont CA

Investigators

Abstract

Abstract for proposal 1559403 PI: Lori Bassman Proposal Title: IRES: US-Australia collaboration on new high strength, high ductility classes of high entropy alloys through intermetallic manipulation Institution: Harvey Mudd College Traditional alloys used in engineering applications consist primarily of one or two elements, with other elements added in relatively small quantities to enhance material properties. However, the inclusion of large quantities of additional elements typically causes alloys to become brittle. Recent work, including that by American undergraduate students working with researchers at the University of New South Wales (UNSW) in Australia and Prof. Lori Bassman of Harvey Mudd College (HMC), has led to the development of novel metal alloys using a new strategy. These advanced alloys, called high entropy alloys (HEAs), have carefully selected compositions with approximately equal amounts of several elements and have demonstrated excellent material properties. This project will greatly expand the range of combinations of elements that can be used to create successful HEAs. With the proposed new strategy will come increased promise for creating alloys with improved combinations of strength, ductility and cost. During ten week periods in the summers of 2017 to 2019, twelve undergraduate students will conduct experimental and computational research at UNSW towards this goal. The lead collaborators, Dr. Kevin Laws and Prof. Michael Ferry in the UNSW School of Materials Science and Engineering, and researchers in the UNSW Electron Microscope Unit have worked with HMC undergraduates for many years. They will continue to provide students with discipline-specific expertise and mentoring unavailable at HMC as well as extensive access to physical metallurgy laboratories, microscope facilities and training. Progress in the HEA field so far has focused on identification of specific systems of elements that can form one or two simple solid solution phases with high thermal stability and no brittle intermetallic phases. In this project new HEAs will be developed by increasing the ductility of intermetallic phases that occur in other systems. Through this alloy development, the students and their UNSW mentors will refine the fundamental principles that govern HEA formation and atomic ordering and explore the deformation mechanisms associated with greatly enhanced strength and ductility in HEAs over conventional alloys. The specific experimental projects to be performed by HMC undergraduates include alloy design, alloy fabrication, mechanical characterization and microstructural characterization. Computational projects will involve first-principles modeling of alloy structures and properties. These experiences will contribute to the maturation of the students into confident, enthusiastic researchers who are prepared for science and engineering careers in international research environments. At least half of the participating students will be female, and underrepresented minority students will be specifically recruited. This research is funded by the IRES program of the NSF Office of International Science and Engineering.