Structure-Property Relationship of Ultrafine Grained
Titanium-Aluminum-Niobium Alloys Processed by Accumulative Roll Bonding
Viola L. Acoff, Ph.D.
The University of Alabama
Department of Metallurgical & Materials Engineering
Wednesday, November 10, 2010
11:00 am – 12 pm
Fung Auditorium
Abstract:
The severe plastic deformation process of accumulative roll bonding (ARB) was used to process ultrafine grained Ti-Al and Ti-Al-Nb alloys from elemental titanium, aluminum, and niobium foils. The multi-layered foils were subjected to various ARB cycles that consisted of repeated cold rolling with interspersed folding of the foils. The structure-property relationship between the number of ARB cycles and the resulting grain size was investigated and characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), x-ray diffraction (XRD), tensile testing and microhardness testing. TEM analysis showed the formation of ultrafine, submicron grains as a result of increasing ARB cycles. The reaction kinetics of solid-state phase transformations that occurred after annealing were also investigated as a function of ARB cycles. A relationship between the grain size and reaction kinetics was developed.
Biosketch:
Dr. Acoff received her B.S. (1989), M.S. (1991) and Ph.D. (1994) degrees in materials engineering from the University of Alabama at Birmingham. She joined The University of Alabama as Assistant Professor in the Department of Metallurgical and Materials Engineering in 1994 and was promoted to the rank of Full Professor in 2004. Since 2009, Dr. Acoff has served as Head of the Department of Metallurgical & Materials Engineering. She teaches undergraduate and graduate courses in welding metallurgy, physical metallurgy and scanning electron microscopy and has an active research group with projects focused on the characterization of advanced materials subjected to welding and joining processes. Dr. Acoff has received numerous national and international awards and recognitions including the Adams Memorial Membership Award for outstanding teaching activities, Best Paper Award for the TMS Symposium on Gamma Titanium Aluminides, Warren F. Savage Memorial Award for best paper, and the National Science Foundation CAREER Award.