NSF-Europe: U.S. - Germany Research Collaboration: "Bridging Length Scales in Deforming Single and Textured Polycrystals of Structural Magnetic Shape Memory Alloys"

Texas A&M Engineering Experiment Station, College Station TX

Investigators

Abstract

The grant explores fabrication of textured FeNiCoTi and CoNiAl magnetic shape memory alloy (MSMA) polycrystals from powder precursors and single crystal growth. A major objective is to characterize the microstructural, physical and magneto-thermo-mechanical (MTM) behavior for better understanding of the mechanisms responsible for magnetically, thermally and mechanically induced strains in MSMAs. Along with the experimental studies, modeling effort will take into account the external magnetic field and texturing. The powders will be prepared by high-pressure gas atomization, oriented along the easy magnetization axis by application of a magnetic field and consolidated by warm equal channel angular extrusion (ECAE) and hot isostatic pressing. Along with mechanical testing under stress, temperature as well as magnetic field, microstructural characterization is planned with in-situ transmission electron microscopy and orientation imaging microscopy, and physical characterization with calorimetry and X-Ray diffraction. The consolidation of metallic powders and modeling of SMAs will be performed at Texas A&M University while thermomechanical characterization will be performed in collaboration with the University of Paderborn with extensive experience on such activities on active powders. The innovative processing of the textured MSMA polycrystals are expected to lead to high field-induced actuation force levels, desired microstructural morphology for magnetic activation, and higher response frequencies compared to conventional SMAs such as NiTi. %%% The proposed research will help to foster local culture of fabricating and using SMAs and magnetic materials for engineering. This will come about not only by educating graduate and undergraduate students directly involved in this project in a collaborative environment with German students and researchers but also by building demonstrations and laboratory experiments into current classroom activities. The investigators plan to use the proposed research to aid in the development of a new graduate-level course on active materials. Other outreach and education activities at Texas A&M will be used to disseminate knowledge gained to mathematics and science K-12 instructors and current high school students from diverse backgrounds. *** This NSF project is co-funded by the Office of Multidisciplinary Activities, the Division of Materials Research (Metals Research) and International Office (Western Europe) as a Cooperative Activity in Materials Research between the NSF and Europe (NSF 02-135). This project is being carried out in collaboration with University of Paderborn in Germany.