Event Title

Local Chemical Environments in Magnetic “High Entropy” Alloys

Presenter Information

Daniel Mukasa, Oberlin College

Location

Science Center A247

Start Date

10-27-2017 3:00 PM

End Date

10-27-2017 4:20 PM

Research Program

California Institute of Technology (CALTECH) WAVE Fellowship

Abstract

Chemical and magnetic ordering in the body-centered cubic high entropy alloy FeCoCrNiAl2 were investigated. The materials were subjected to thermal treatments by various methods including melt spinning and arc melting followed by quenching from various temperatures. Previously measured magnetic properties have shown a dependence on thermal treatment, raising the belief that such treatments have altered the local chemical environments in this multicomponent alloy. The local chemical arrangements around Fe atoms were studied by 57Fe Mossbauer spectroscopy at both room temperature and at 77K where the samples are strongly ferromagnetic. Preliminary results show that the different thermal treatments altered the local chemical environments in the alloy. These results will be correlated to changes in the bulk magnetic properties with thermal treatment. Changes in the configurational entropy of these "high entropy" alloys will also be estimated.

Notes

Session I, Panel 3 - Physical | Science
Moderator: Jason Stalnaker, Associate Professor of Physics

Major

Physics; Mathematics

Project Mentor(s)

Brent Fultz, Applied Physics & Materials Science, Caltech

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Oct 27th, 3:00 PM Oct 27th, 4:20 PM

Local Chemical Environments in Magnetic “High Entropy” Alloys

Science Center A247

Chemical and magnetic ordering in the body-centered cubic high entropy alloy FeCoCrNiAl2 were investigated. The materials were subjected to thermal treatments by various methods including melt spinning and arc melting followed by quenching from various temperatures. Previously measured magnetic properties have shown a dependence on thermal treatment, raising the belief that such treatments have altered the local chemical environments in this multicomponent alloy. The local chemical arrangements around Fe atoms were studied by 57Fe Mossbauer spectroscopy at both room temperature and at 77K where the samples are strongly ferromagnetic. Preliminary results show that the different thermal treatments altered the local chemical environments in the alloy. These results will be correlated to changes in the bulk magnetic properties with thermal treatment. Changes in the configurational entropy of these "high entropy" alloys will also be estimated.