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Development of a Simplistic Method for Processing Intermetallic Sheet Materials Using Cold Roll Bonding and Reaction Annealing,

Viola L. Acoff, The University of Alabama,MET DMR-0206826

Objectives:•Simplification of the processingof intermetallic sheets from elementalFoils• Development of an analytical model

Analytical Model:Further advances have been made to the analytical model that was developed, which is the first to address the rolling of multiple sheets. The model was applied to Ti-Al system and a good agreement was observed when the model results were compared with the experimental results. The model is currently being modified to accommodate the Ti-Al-Nb system.

Process Simplification:Ti-46Al-9Nb (at.%) multi-layered composites were successfully produced using the cold roll bonding process (Figure 1). Besides the annealing temperature and time, rolling strain also has a significant effect on the microstructures, grain size and new phase formation. High rolling strain promotes the formation of ultrafine grains. This results in an increase in grain boundaries and dislocations, which accelerates the diffusion of each element layer and enhances the formation of intermetallic compounds (IMC). In addition, increasing the rolling strain decreases the reaction formation temperature of intermetallic compounds (Figure 2).

Figure 1Figure 2. DTA plots of specimens subjected to the following plastic strain amounts a) 2.4, b) 4.0, c) 7.2, and d) 8.8. The respective IMC reaction temperatures are denoted.

Heat Flow (mW) Exo.Temperature (ºC)

a)b)

d)

c)960ºC

940ºC

860ºC

860ºC

Development of a Simplistic Method for Processing Intermetallic Sheet Materials Using Cold Roll Bonding and Reaction Annealing,

Viola L. Acoff, The University of Alabama,MET DMR-0206826

Broader Impact:•The PI is also PI of another NSF funded project entitled “Introducing Science Faculty from Historically Black Colleges and Universities to Materials Science and Engineering.” The PI has used some of the results of the current research project in the workshop presentation materials. • The PI has been approached by two different companies that are interested in adopting the process. The PI has forwarded these requests to the Intellectual Property Committee here at The University of Alabama.

Education:• Two graduate students, oneundergraduate student, and onePost-Doc have been involved with this project.• One graduate student received his Ph.D. in 2005 and the other is a Ph.D. candidate.• The senior thesis of a former undergraduate student, Prentice Singleton, was related to this project. He performed fusion welding on the as-rolled multi-laminated sheets that were developed by the grad students. Results showed that the dominant intermetallic compound that forms in the heat-affected zone is TiAl2, not TiAl3, which dominates during controlled annealing. His poster on this project won the 2005 TMS Student Poster Contest. Prentice is currently a graduate student at The University of Alabama.

Former undergraduate studentPrentice Singleton at the 2005TMS Student Poster Contest inSan Francisco, CA.