# Presentation: 482852

## CAREER: Robust Thin Film Shape Memory Alloys for MEMS Ainissa G. Ramirez, Yale University, DMR 0347095 

**Motivation**
- Thin film shape memory alloys are potential actuation materials in microelectromechanical systems (MEMS). Unfortunately, these materials are compositionally sensitive and require a high-temperature crystallization step to create their actuating (crystalline) form.  An understanding of the development of the microstructure during annealing enables researchers to make more informed decisions about processing conditions for specific properties.  Using theoretical models, this research thrust has developed an understanding of the microstructural evolution during crystallization. This work is currently embarking on linking the processing and microstructures to their associated properties.
*Nanoindentation of  Ni-Ti Thin Films P.D. Tall, S. Ndiaye, A.C. Beye, Z. Zong, W. O. Soboyejo H. –J. Lee, A. G. Ramirez and K. Rajan  Materials and Manufacturing Process, Vol. 22, (2007) pp. 175-179 *
*Crystallization of Amorphous Sputtered NiTi Thin Films Hoo-Jeong Lee, Hai Ni and Ainissa G. Ramirez Materials Science and Engineering: A Vol. 438  (2006)  pp. 703-709*

- Using *in situ* transmission electron microscopy (pictured above), we can determine the nucleation (*J**o*) and growth (*V**o*) rates and use them to  _***predict***_ the average grain size (*d*) over a range of temperatures.

- Using nanoindentation, we can determine the effect of composition on the mechanical properties of NiTi thin films.

## CAREER: Robust Thin Film Shape Memory Alloys for MEMS Ainissa G. Ramirez, Yale University, DMR 0347095 

**Broad Impact:**
- Our method of experimentally determining the kinetic parameters of crystallization with TEM, and then inserting these values into the Avrami theory allows us to predict microstructure and tailor the associated properties of a film *a priori*. This work will impact fields such as geology, physical chemistry, materials science, and biochemistry and has been profiled in the *MRS Bulletin*, *R&D Magazine, *and the *MIT news*.
**Education:**
- Revamped the *Introduction to Materials Science* class by incorporating classroom demonstrations. The student enrollment has doubled.
*Training:*  Drs. Xu Huang, Hoo-Jeong Lee, Hai Ni and Mr. Ye Xu contributed largely to this research.  Senior project advisor to: Joshua Calabro, Joseph Aphinyanphongs
*Collaborations*: Researchers at MIT, Ohio State University, and Columbia University also contributed to this work.
*Mentored: *Numerous engineering students at Yale and MIT.

**Outreach: **
- Created and hosts an award-winning science lecture series for kids (ages 7th grade and up) called *Science Saturdays.  *Four lectures of various science topics are held each semester with average attendances of over 110 people. Lectures are available by streaming video on *www.sciencesaturdays.org* and DVDS are available to schools and libraries.
- Wrote a materials science classroom demonstrations book, called *Demoworks, *which is affiliated with the StrangeMatter at www.strangematterexhibit.com/teachers.html.  It has over 15,000 hits since its inception (2004).
- Serves as an advisor to the NISE Network (Exploratorium/Boston/Minnesota); serves as an advisor to  the Liberty Science Center (NJ) and the Exploratorium.

- CAREER: Robust Thin Film Shape Memory Alloys for MEMS Ainissa G. Ramirez, Yale University, DMR 0347095