UNIVERSITY OF CALIFORNIA, SAN DIEGO Phase Transformations in Nickel-rich Nickel-Titanium Alloys: Influence of Strain-rate, Temperature, Thermomechanical Treatment and Nickel Composition on the Shape Memory and Superelastic Characteristics A dissertation submitted in partial satisfaction of the requirements for the degree Doctor of Philosophy in Materials Science and Engineering by Raghavendra R. Adharapurapu Committee in charge: Professor Kenneth S. Vecchio, Chair Professor Prabhakar R. Bandaru Professor Sungho Jin Professor John B. Kosmatka Professor Robert O. Ritchie 2007