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The superelastic stress-strain response of [100] Co 49 Ni 21 Ga 30 single crystals in tension showing how thermo-mechanical history and microstructure.

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Presentation on theme: "The superelastic stress-strain response of [100] Co 49 Ni 21 Ga 30 single crystals in tension showing how thermo-mechanical history and microstructure."— Presentation transcript:

1 The superelastic stress-strain response of [100] Co 49 Ni 21 Ga 30 single crystals in tension showing how thermo-mechanical history and microstructure influence the transformation hysteresis. Ab-initio calculated atomic displacements along [110] (left) and phonon dispersions (right) leading to cubic-to-tetragonal transformation in Co 2 NiGa Shape Memory Alloys. Computational and Experimental Design of Novel CoNiGa High Temperature Shape Memory Alloys (HTSMAs) Raymundo Arroyave, Texas Engineering Experiment Station, DMR 0805293 The ultimate goal of the current work is to develop CoNiGa HTSMAs through a combined computational/experimental approach. The intellectual merits of this transformative research are: –The potential of revolutionizing the field of SMAs, by developing SMAs possessing high TTs, high thermal stability, low susceptibility to creep, aging and cyclic damage as well as good ductility –Transformation of the design process for new HTSMAs through the synergistic experimental-computational approach –The creation of an entirely new family of SMAs, i.e. shape memory superalloys, with very high temperature SM and PE properties. Research Highlights: –A Thermodynamic model for the Co-Ni-Ga system is being developed. It will be used in the design of microstructure of polycrystalline Co-Ni-Ga alloys. –Ab initio calculations have been used to elucidate the microscopic mechanisms for the cubic-to-tetragonal transformation in Co 2 NiGa alloys. –We have discovered a composition with the largest superelastic temperature window for a SMA reported to date and a composition with the highest phase transformation temperature in the CoNiGa alloy system. –Compositions in the CoNiGa alloy system with the highest known transformation temperatures are fabricated. Their shape memory response is under investigation.

2 Computational and Experimental Design of Novel CoNiGa High Temperature Shape Memory Alloys Raymundo Arroyave,Texas Engineering Experiment Station, DMR 0805293 The broader impacts of the proposed activity are reflected in the following areas: –Maintaining US leading role in active materials research despite the vast amount of recent works at overseas on SMAs –Development of teaching modules for incorporation into undergraduate courses –Helping K-12 students in developing science projects with SMAs –Enriched graduate and undergraduate research experiences in coordination with the new IGERT and Nanomaterials certificate programs –Development of a graduate course in computational materials science –Involvement of underrepresented groups –Disseminating the knowledge generated to both academia and industry through the workshops and symposiums on SMAs, presentations, publications, and a website, and close collaboration with industry. Broader Impact Highlights: –Four students (including one female and one Hispanic), two M. S., one Ph. D., and one undergraduate are employed in the project. –A course on thermodynamics of materials and applications of computational thermodynamics has been developed and offered during Spring 2008. It will be offered again during Spring 2010. –Ongoing interaction with a local high school for new science projects. One of the students, Mr. Druck Green, an eighth-grade student from Harmony Science Academy – a charter school, placed first in a state level competition and third in an international competition (International Sustainable World (Energy, Engineering, Environment) Project Olympiad, www.isweeep.org).www.isweeep.org –The PI and Co-PI have been active in the ISWEEP Olympiad as judge and member of the organizing committee, respectively, for the last two years. Also they have been involved in recruitment activities at Minority Institutions, such as the University of Texas- Pan-American and assisted in the organization of a Materials Camp for Teachers –The Co-PI has organized three international symposiums and two workshops for oil/gas, aerospace, and automotive industry on SMAs. –Two research articles have been published, one in press, and two in review.


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