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1. Strain Rate Effects on Interstitial Diffusion Controlled Twinning in Alpha- TitaniumSreeramamurthyAnkem, University of Maryland, College Park, DMR 0906994 The PI and his coworkers have shown that twinning can be a diffusion controlled process in certain cases, unlike the traditional understanding that twinning is a purely shear and shuffle process. Recently, this was confirmed by studying the effect of strain rate on twin thickness in single phase alpha titanium. Further, a diffusion model has been proposed that predicts twin thickness as a function of strain rate with good accuracy. These results will be helpful in designing Ti alloys with improved low-temperature creep resistance (Figure 1) Micrograph showing twin thickness after tensile deformation to 3% strain for two strain rates: (a) 10-4/s and (b) 10-6/s [ref]. (Figure 2) Twin thickness and number of twins per unit area across four strain rates. Increase in twin thickness with decrease in strain rate is not expected from classical theory but is predicted by an oxygen diffusion based model. Data from [ref]. [ref] Wyatt, Z.W., Joost, W.J., Zhu, D., Ankem, S., Int. J. Plasticity, In Press (2012). Figure 1 10-2 10-6 10-4 10-1 (a) (b) Figure 2

2. Strain Rate Effects on Interstitial Diffusion Controlled Twinning in Alpha- Titanium SreeramamurthyAnkem, University of Maryland, College Park, DMR 0906994 Education: The PI is the founding and current Faculty Advisor for the Material Advantage Student Chapter at the University of Maryland. This chapter is very active in various programs at the University of Maryland, as well as promoting members to attend the local and national professional society meetings. In addition to advising the student chapter, the PI involves both undergraduate and graduate students in the research programs. Two graduate students have been involved with this project over the last year. During the current year Dr. Zane Wyatt (graduate student) graduated with his PhD. Mr. Will Joost (graduate student) continues to work on the project and towards his PhD. Outreach: The findings of this investigation have been presented at various national and international conferences and institutions, and published in reputed journals. They include: Wyatt, Z.W., Ankem, S., “Advances in Low Temperature (<0.25Tm) Creep Deformation Mechanisms of alpha, beta, and alpha + beta titanium alloys.” Proceedings of the 12th World Conference on Titanium. Beijing, China. June 2011. pgs 862-869. Ankem, S., Joost, W.J., Wyatt, Z.W., “The Role of Interfacial Interaction Stresses and Crystallography on Deformation Mechanisms in Two-Phase Titanium Alloys.” Keynote presentation at 2012 TMS Annual Meeting, Orlando, FL, 03/14/2012. Wyatt, Z.W., Joost, W.J., Zhu, D., Ankem, S., “Deformation Mechanisms and Kinetics of Time-dependent Twinning in an alpha-titanium Alloy.” International Journal of Plasticity, In Press (2012). Ankem, S., Joost, W.J., Wyatt, Z.W., “Dynamics of Time-dependent Twinning During Low-temperature Creep of Titanium Alloys.” Presented at the International Symposium on Plasticity, 2012, San Juan, PR, 01/03/2012.