MSE Seminar: Lee Casalena, Development of viable high-temperature shape memory alloys

PhD Candidate advised by Dr. Michael Mills

All dates for this event occur in the past.

264 MacQuigg Labs
105 W. Woodruff Ave.
Columbus, OH 43210
United States

Abstract

The development of viable high-temperature shape memory alloys demands a coordinated effort connecting nanoscale crystal structure to macroscale mechanical properties. In this work, several high performance NiTiHf and NiTiAu alloys are comprehensively explored with the goal of enhancing properties conducive to actuator applications in demanding automotive and aerospace environments.

NiTiHf has a favorable balance of properties, including high strength, stability and work output at temperatures approaching 300oC, yet at reduced cost compared with Pt/Pd/Au containing counterparts. NiTiAu demonstrates work output at significantly higher temperatures – where the benefits may offset cost – but further research is needed.

Advanced electron and high energy X-ray characterization techniques are used to explore the effects of precipitate structure, coherency, chemistry, and density on alloy behavior to develop an understanding of the critical microstructure-property relationships. These insights are incorporated into microstructural modeling frameworks to further reveal how phase transformations and time-dependent plasticity interact under isothermal deformation and load-biased thermal cycling conditions.

Bio

Lee completed his bachelor’s degree in chemistry and materials science in 2011 at the University of Cape Town, South Africa. After meeting Professor Hamish Fraser during his senior year, he came to Ohio State for an internship during the summer of 2012. The enriching experience led him to apply to only one graduate program. Lee joined the Mills group soon after for a PhD in shape memory metallurgy. His research has primarily used aberration-corrected electron microscopy to advance several high temperature shape memory alloys, collaborating with researchers at NASA and three major national laboratories. In 2015 he was awarded a Presidential Fellowship for his research efforts. In his spare time, Lee enjoys traveling, building clocks, frequenting all-you-can-eat buffets, camping, photography, and the RPAC hot tub. He moves to Portland, Oregon in June where he has accepted a position at FEI as an Applications Engineer in the field of transmission electron microscopy.