Advanced Manufacturing, Processing, Characterization and Modeling of Functional Materials: Advanced Manufacturing, Processing, Characterization and Modeling of Functional Materials I
Program Organizers: Mohammad Elahinia, University of Toledo; Haluk Karaca, University of Kentucky; Reginald Hamilton, Pennsylvania State University; Mohammad J. Mahtabi; Narges Shayesteh Moghaddam, University of Texas at Arlington; Reza Rizvi, University of Toledo; Markus Chmielus, University of Pittsburgh; Hamdy Ibrahim, University Of Tennessee Chattanooga; Mohammadreza Nematollahi, University Of Toledo
Wednesday 8:00 AM
November 4, 2020
Room: Virtual Meeting Room 21
Location: MS&T Virtual
Session Chair: Markus Chmielus, University of Pittsburgh; Keyvan Safaei, University of Toledo
8:00 AM
3D Printed Shape Memory Polymers: Electronics and Morphing: Trenton Cersoli1; Pedro Cortes1; 1Youngstown State University
The present work has investigated the 3D printing process of a shape memory polymer (SMP) based polyurethane using material extrusion technology. Here, SMP pellets were fed into the printing unit, and smart coupons were manufactured. In contrast to the conventional film-casting manufacturing processes of SMPs, the use of 3D printing allows the production of complex parts for flexible electronics and morphing structures. The manufactured SMP parts were here assisted by SMA wires in order to induce actuation forces on the morphing components. The memory performance of a number of actuating structures were investigated and their fundamental recovery and mechanical properties were characterized. The preliminary results show that the assembled structures were able to recover their original conformation following a heating input. It seems that the incorporation of SMAs with SMPs results into hybrid smart structures where the SMP provides the fixating phase and the SMA the recovery stress phase.
8:20 AM
Establishing Fundamentals for Laser Metal Deposition of Functional Ni-Mn-Ga Alloys: Effect of Rapid Solidification on Microstructure and Phase Transformation Characteristics: Emily Flitcraft1; Carolin Fink1; Markus Chmielus2; Jakub Toman2; 1Edison Joining Technology Center - OSU Welding Engineering; 2University of Pittsburgh
Laser-based additive manufacturing holds the promise of enabling complex geometries for shape memory alloy components. However, rapid melting, resolidification and multiple reheating create challenging microstructures characteristic of non- or low-functional alloys. We investigate how non-equilibrium processing and complex thermal cycling effect microstructural evolution and functional properties in Ni-Mn-Ga magnetic shape memory alloys. This talk gives insight into our efforts to establish cooling rate-microstructure-magnetic property relations that will help identify processing conditions for laser metal deposition (LMD) of functional Ni-Mn-Ga alloy. Physical simulation of rapid solidification achieved cooling rates that resemble what is seen in LMD (100-10000 K/s). Microstructure characterization was performed as a function of cooling rate using scanning electron microscopy, electron dispersive spectroscopy, and X-ray diffraction. The effect of cooling rate on phase transformation characteristics was investigated using differential scanning calorimetry. If available at time of presentation, results from magnetic property measurements using vibrating-sample magnetometer will also be included.
8:40 AM
Microstructure and Property Differences in Sintered and Annealed Binder-Jet 3D Printed Ni-Mn-Ga Magnetic Shape Memory Alloys: Aaron Acierno1; Ville Laitinen2; Jakub Toman1; Katerina Kimes1; Mirko Boin3; Robert Wimpory3; Andrey Saren2; Kari Ullakko2; Markus Chmielus1; 1University of Pittsburgh; 2Lappeenranta-Lahti University of Technology; 3Helmholtz-Zentrum Berlin
Ni-Mn-Ga Heusler alloys are multifunctional metals that demonstrate macroscopic deformation under an externally applied magnetic field by the motion of martensitic twin boundaries. Neutron diffraction analysis identified the martensite modulation and observed the grain size evolution in binder-jet 3D printed Ni-Mn-Ga samples sintered at 1080 °C and 1090 °C. Large clusters of high neutron-count pixels in samples sintered at 1090 °C were identified,suggesting Bragg diffraction of large grains compared to 1080 °C sintered samples, which was confirmed by quantitative stereology. Greater resistance to plasticity was noted in 1090 °C sintered samples through nanoindentation as a result of the increased densification. An upward shift of a few degrees in major structural and magnetic transformation temperatures was seen in 1090 °C sintered samples. Additionally, twin variants on the order of ≤10 μm in width were observed and the origin of magnetic anisotropy verified through magnetic force microscopy (MFM).
9:00 AM
Epitaxial growth of a magnetic shape-memory alloy via laser melting and directed energy deposition: Jakub Toman1; Tyler Paplham1; Peter Müllner2; Markus Chmielus1; 1University of Pittsburgh; 2Boise State University
Magnetic shape-memory alloys (MSMAs) elongate when driven by a magnetic field, with strains as high as 12 % reported in material free of grain boundaries. MSMAs have been used in prototype actuators, micro-pumps and sensors. Output force is a limiting factor for actuators, and is dependent on cross-sectional area and thus decreased by porosity. While other efforts in 3D printing or additive manufacturing of MSMAs leverage high porosity in pursuit of functionality, production of fully-dense MSMA with high maximum strain may be possible by directed energy deposition upon single crystals. Under exclusively epitaxial growth, deposited tracks would have no grain boundaries. To investigate this process, we produced systematic laser-melted tracks. Low powers and velocities solidified epitaxially, with rare stray grains, while higher-valued parameters produced significant stray grain content. Additionally, Ni-Mn-Ga powder was deposited in tracks. Selected tracks of both types were later heat treated.
9:20 AM
Compressive Behavior of NiMnGa Parts Fabricated by Binder Jet Additive Manufacturing: Stephen Isacco1; Christopher Bansah1; Matthew Caputo2; Constantin Solomon1; 1Youngstown State University; 2Penn State University
Solid and gyroid cube geometries had been fabricated by binder jet additive manufacturing from NiMnGa prealloyed powders. Sintering of cured parts was performed at temperatures between 1000</0>C and 1080</0>C for time intervals up to 20.5 hours. The compressive stress-strain curves were determined by combining the stress values calculated using the calibrated loading cell and sample geometry, and the strain calculated using digital image correlation and tracking. The sintering conditions are responsible for part’s final density, which play a determinant role in the part’s compressive behavior. Fracture analysis of compressed parts indicate a dual trans-, inter-granular brittle failure mechanism. Numerical modeling of part’s compressive behavior was performed using ANSYS Workbench. In order to account for part porosity, the part model was obtained by micro CT scanning of a 3D printed part. Good qualitative agreement had been obtained between the model and experimental data for compressive behavior of 3D printed NiMnGa parts.