CAREER: Neutron, Synchrotron X-ray Diffraction and Instrumented Indentation Studies of Deformation in Shape-Memory Alloys

The University Of Central Florida Board Of Trustees, Orlando FL

Investigators

Abstract

Shape-memory alloys are of theoretical and commercial interest for the deformation phenomena they exhibit - twinning and stress-induced or temperature-induced phase transformations. The proposed program uses neutron diffraction, synchrotron X-ray diffraction and instrumented indentation to investigate deformation in shape-memory alloys. The emphasis is on in situ diffraction measurements, i.e., simultaneously recording diffraction spectra from samples that are subjected to external stresses or temperature changes, or a combination thereof. Such measurements provide quantitative information of the evolving internal strains, texture and phase volume fractions during twinning and stress-induced or temperature-induced phase transformations. The experiments will utilize the neutron beam at Los Alamos National Laboratory and the synchrotron X-ray beam at Argonne National Laboratory. Consistent with the theme of investigating deformation in shape-memory alloys and with the objective of obtaining mechanical properties from small sampling volumes of shape-memory alloys, instrumented indentation experiments will be performed on shape-memory alloys to correlate load-depth data from indentation experiments with macroscopic stress-strain data from conventional tests. The program is expected to further the understanding of (a) shape-memory alloys for actuator applications and for biomedical applications, as shape-memory alloys continue to make inroads as the material of choice for stents, and (b) neutron diffraction, synchrotron X-ray diffraction and instrumented micro- and nanoindentation as valuable tools for mechanical characterization of internal stresses in emerging materials, bulk, coatings, thin-films, line and dot forms. The educational activities include curriculum development, instruction and laboratory development providing experience and training for students using facilities at National Laboratories. Outreach and mentoring activities include collaboration with a local science center and the Minority Engineering and Computer Science Office at UCF, engineering education in the work place through distance education in the Florida Engineering Education Delivery System (FEEDS) and the development of industry short-courses.