Advanced Processing Techniques: Additive, Porous, and Others: Poster Session
Program Organizers: Aaron Stebner, Colorado School of Mines
Monday 5:30 PM
July 10, 2017
Room: Crystal Ballroom A
Location: Hyatt Regency Chicago
P1-1: A Novel Micro-nano Dual-scale Porous Cu-Zn-Al Shape Memory Alloy Composite Current Collector with a Layer of β and Cu on the Ligament by One-step Dealloying Method: Luo Zheng1; Yuan Bin1; 1South China University of Technology
A novel micro-nano dual-scale porous Cu-Zn-Al composite with a layer of β phase shape memory alloy and nano-size Cu on the ligament was fabricated by one-step dealloying of Cu-34Zn-6Al precursor with a dual β and γ phase in a HCl-FeCl3 solution and subsequent heat treatment. The pore and microstructure evolutions during dealloying and heat treatment were studied by XRD, SEM and TEM. The formation of micro- and nano- porous structure is attributed to the dealloying of γ phase and preferential dissolution of Zn and Al atoms in the β phase. During subsequent heat treatment, the diffusion of zinc and aluminum atoms can be clearly observed and a new layer of β phase emerges on the ligament, also the dual-scale porous structure can be well preserved after heat treatment. The dual-scale porous composite is an ideal candidate as current collector in a lithium-ion battery with high capacity and cycling life.
P1-2: Anisotropic Deformation and Different Mechanisms of Superplasticity in Polycrystalline Ni-Mn-Ga Alloys under Uniaxial Tension: Longsha Wei1; Xuexi Zhang1; Mingfang Qian1; Lin Geng1; 1Harbin institute of technology
Ni–Mn–Ga alloys have for decades received attention owing to their multi-functional properties such as magnetic-field-induced strain. However, such alloys are extremely brittle at ambient temperature. Here, we present a polycrystalline Ni47.4Mn31.5Ga21.1 alloy, exhibiting strongly anisotropic deformation and excellent superplastic capacity with different microstructures. For the columnar grains along <001> obtained at as-cast state, Ni47.4Mn31.5Ga21.1 alloy exhibits brittle fracture at loading axis perpendicular to <001> direction and ductile behavior over 100% elongation at parallel to <001> direction at 700°C. However, Ni47.4Mn31.5Ga21.1 alloy displays ductile behavior in two directions with different flow stress at 800°C. The superplastic mechanism is attributed to dislocation glide and dynamic recovery with maximum elongation of 137%. For the extruded rod with equiaxed grains and <111> texture, the superplastic mechanism is dislocation glide and dynamic recrystallization with maximum elongation of 319%. The present work opens a realistic sight to fabricate complex engineering components by superplastic deformation.
P1-3: Binder Jet 3D Printing of Magnetocaloric Materials: Katerina Kimes1; Erica Stevens1; Jakub Toman1; Amir Mostafaei1; Markus Chmielus1; 1University of Pittsburgh
Magnetocaloric (MC) materials have been intensely studied due to their ability of exhibiting a large adiabatic temperature change when magnetized. This positions them uniquely for the use in magnetic refrigeration, which is more efficient than traditional refrigeration. This study focuses on the characterization of Powder Bed Binder Jet (PB-BJ) printing of MC foams. Alloys studied include Ni-based Heusler alloys. Samples are printed using a custom-designed printer for small amounts of powder. The feedstock powder composition, microstructure, martensite phase transformation, magnetic and magnetocaloric properties are characterized and compared to printed and sintered samples. We will further report the influence of the sintering temperature on densification, porosity characteristics, magnetization, hierarchical twinning and compositional variations throughout particles especially at their surfaces. Entropy data are calculated from temperature-dependent magnetization measurements to compare the magnetocaloric effects of additively manufactured MC materials to bulk MC materials.
P1-4: Contact Pressure and Residual Strain of Resistance Spot Welding on Mild Steel Sheet Metal: Yuanxun Wang1; Yiping Chen1; 1Huazhong University of Science and Technology
Coupled electrical-thermal and thermo-elastic-plastic analyses were performed to analyze the behavior of the mechanical features during the resistance spot welding (RSW) process including the squeeze, heating and hold steps, and to prepare for further structural analysis for large complex structure with large quantity of resistance spot welds. A two-dimensional axisymmetric thermo-elastic–plastic FEM model was developed and analyzed in the commercial FEM program, ANSYS. The analysis was based on the transient temperature field obtained from a transient electrical–thermal simulation of RSW process conducted by the authors. The distribution and change of the contact pressure at the electrode–workpiece interface and faying surface, the residual stress and residual plastic strain distribution of the weldment were obtained through the analysis.