Design of Transforming Materials

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This award is funded under the American Recovery and Reinvestment Act of 2009(Public Law 111-5). The research objective of this award is to develop a science-based design methodology that can be extended to create materials undergoing stress-induced phase transformation with superior properties. The work proposes to advance knowledge in design of new transforming materials that potentially exhibit extraordinary shape memory and fatigue properties, and tailored hysteresis with potential applications in transducers, actuators, and sensors. The proposed novel experiments and advanced DIC (digital image correlation) techniques at macro- and micro- scales will simultaneously utilize multiple lenses with high resolution capabilities to establish precisely the onset of phase nucleation and growth, and local strains. The proposed experiments are necessary to guide theoretical treatments. Theexperiments will provide a critical check on theory, which considers forward and reverse energy paths, and the stress hysteresis is predicted based on the underlying energetics. The work will develop further understanding of mechanical response of emerging, next generation shape memory materials with Ni, Fe, Mn and Ga constituents. This methodology paves the way for designing materials with transformation reversibility tailored for specific applications.Overall, the work will lay the foundation for a better understanding of the mechanical response leading to the development of new shape memory alloys. At the same time, in the case of iron- based alloys, the transformation during processing and in-service controls the mechanical response; predictive models are essential but missing. The educational impacts include the introduction of a course in the engineering curriculum that specifically links the theory and experiment addressing the issues associated with phase transformations. The plan is to incorporate the results of our research in a short course that is offered biannually in the areas of cyclic deformation and fatigue.