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Modeling Interstitial Diffusion Controlled Twinning in Alpha- Titanium Sreeramamurthy Ankem, 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 process. Recently, they have modeled how twinning during creep of HCP materials such as alpha titanium can be controlled by the diffusion of oxygen. These results clearly show how twinning enhanced mechanical properties can be controlled by controlling the interstitial elements in various materials [ref]. (Figure 1) (a) An HCP cell illustrating the location of titanium and interstitial (where oxygen can reside) lattice sites. The {11-20} plane onto which the projection is made is shaded in gray. (b) Projection of the HCP lattice onto the {11-20} plane [ref]. (Figure 2) (a) Schematic illustration of {10-12} twinning. Figure 1 Figure 2
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Modeling Interstitial Diffusion Controlled Twinning in Alpha- Titanium Sreeramamurthy Ankem , University of Maryland, College Park, DMR 0906994. - PowerPoint PPT Presentation
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Modeling Interstitial Diffusion Controlled Twinning in Alpha- TitaniumSreeramamurthy Ankem, 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 process. Recently, they have modeled how twinning during creep of HCP materials such as alpha titanium can be controlled by the diffusion of oxygen. These results clearly show how twinning enhanced mechanical properties can be controlled by controlling the interstitial elements in various materials [ref].
(Figure 1) (a) An HCP cell illustrating the location of titanium and interstitial (where oxygen can reside) lattice sites. The {11-20} plane onto which the projection is made is shaded in gray. (b) Projection of the HCP lattice onto the {11-20} plane [ref].(Figure 2) (a) Schematic illustration of {10-12} twinning. Shear of the lattice to in the <-110-1> direction is shown . (b) Reorientation of the lattice eliminates octahedral sites marked with an “X” where an oxygen atom could reside [ref].
[ref] P.G. Oberson, Wyatt, Z.W., Ankem, S., Scripta Materialia 65 (2011) 638-641.
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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, two undergraduate students, and one visiting professor have been involved with this project over the last year. During the current year, Mr. Zane Wyatt (graduate student), Mr. Will Joost (graduate student), Mr. Alex Kao (undergraduate student), Ms. Komal Syed (undergraduate student), and Mr. Dachuan Zhu (visiting professor) have been involved with this project.
Outreach: The findings of this investigation have been presented at various international conferences and institutions, and published in reputed journals. They include:
1) Ankem, S., Wyatt, Z.W., “Advances in Low Temperature (<0.25Tm) Creep Deformation Mechanisms of alpha, beta, and alpha + beta titanium alloys.” Presented at the12 th World Conference on Titanium. Beijing, China. June 2011.
2) Ankem, S., “Advances in Low Temperature Creep Deformation Mechanisms of alpha, beta, and alpha + beta Titanium Alloys.” Invited Presentation, The University of Hyderabad, August 2011.
3) Wyatt, Z.W., Ankem, S., “Advances in Low Temperature (<0.25Tm) Creep Deformation Mechanisms of alpha, beta, and alpha + beta Titanium Alloys”. To be published in the Conference Proceedings of 12th World Conference on Titanium.
4) Oberson, P.G., Wyatt, Z.W., Ankem, S., “Modeling interstitial diffusion controlled twinning in alpha titanium during low-temperature creep”, Scripta Materialia (65). 2011. 638 – 641.
Modeling Interstitial Diffusion Controlled Twinning in Alpha- Titanium Sreeramamurthy Ankem, University of Maryland, College Park, DMR 0906994
