2007 Everhart Lecture Series
Samantha Daly, Graduate Student in Mechanical Engineering
"Metals with Memory: How these amazing materials remember their shape"
Thursday, February 22, 4-5pm
101 Guggenheim Lab, Lees-Kubota Lecture Hall
Refreshments at 3:45PM
The Everhart Lecture Series is a forum to encourage interdisciplinary interaction among graduate students and faculty, to share ideas about recent research developments, problems and controversies, and to recognize exemplary presentation and research abilities. Lecturers discuss scientific topics at a level suitable for graduate students and faculty from all fields while addressing current research issues.
Abstract: As the science of materials has evolved, we have gained the ability to make unusual alloys that do not exist in nature but have properties advantageous in practical applications. As we enter a generation where greater demands are being put upon material functionality, particularly in biomedical and small-scale applications, it is increasingly important that we are able to characterize and understand how these materials work. Establishing a relationship between the microscopic behavior of a material and its macroscopic properties facilitates the development of these types of new materials and the prediction of their behavior in practical applications.
One prominent example of this type of engineered material is nitinol. Nitinol is a mixture of Nickel and Titanium that has the ability to elastically ÒstretchÓ far beyond most metals (superelasticity) and also has the ability to remember a previous shape when heated (the shape memory effect). It achieves this by changing the geometry of its crystalline structure. This transformation between phases is the fundamental mechanism behind its unique properties, but there is little experimental data characterizing how this transformation proceeds. By using a relatively new technique called Digital Image Correlation (DIC), we have succeeded in getting the first quantitative understanding of how this transformation mechanism nucleates and proceeds. This talk will introduce the shape memory effect and superelasticity, describe the physics behind these phenomena, and discuss the current and future applications of these materials.