Grain Size Effects in Selective Laser Melted Fe-Co-2V

The material science of additive manufacturing (AM) has become a significant topic due to the unique way in which the material and geometry are created simultaneously. Major areas of research within inorganic materials include traditional structural materials, shape memory alloys, amorphous materials, and some new work in intermetallics. The unique thermal profiles created during selective laser melting (SLM) may provide new opportunities for processing intermetallics to improve mechanical and magnetic performance. A parameter set for the production of Fe-Co-2V material with additive manufacturing is developed and efforts are made to compare the traditional wrought alloy to the AM version of the same chemistry. Evaluation includes magnetic properties, composition, and phase as a function of thermal history, as well as mechanical performance. Results show significant similarities in microstructure between AM and wrought materials, as well as mechanical and magnetic performance. Property trends are evaluated as a function of grain size and show effects similar to the Hall-Petch strengthening observed in wrought material, though with some underprediction of the strength. Magnetic properties qualitatively follow the expected trends but demonstrate some deviation from wrought material, which is still unexplained

Mechanical Properties of Heusler Alloys

Heusler alloys have been a significant topic of research due to their unique electronic structure, which exhibits half-metallicity, and a wide variety of properties such as magneto-calorics, thermoelectrics, and magnetic shape memory effects. As the maturity of these materials grows and commercial applications become more near-term, the mechanical properties of these materials become an important factor to both their processing as well as their final use. Very few studies have experimentally investigated mechanical properties, but those that exist are reviewed within the context of their magnetic performance and application space with specific focus on elastic properties, hardness and strength, and fracture toughness and ductility. A significant portion of research in Heusler alloys are theoretical in nature and many attempt to provide a basic view of elastic properties and distinguish between expectations of ductile or brittle behavior. While the ease of generating data through atomistic methods provides an opportunity for wide reaching comparison of various conceptual alloys, the lack of experimental validation may be leading to incorrect conclusions regarding their mechanical behavior. The observed disconnect between the few available experimental results and the numerous modeling results highlights the need for more experimental work in this area

A Laboratory-Based Investigation on Biodegradation and Bioremediation of Oil Contaminants in the Environment

This instructional material was created at the 2011 ATEEC Fellows Institute, with the theme of bioremediation of contaminants in the environment. The material provides three learning activities for use in the classroom/laboratory. The activities will provide practice in the use of the scientific method, development of laboratory techniques, experimental design, the interpretation of experimental results, and the ability to understand the role of science within our larger society. Activity three can also be used to introduce students to careers in the oil spill response and regulatory fields as well as to help them understand the stakeholders involved when oil spills occur. This resource is free to download. Users must first create a login with ATEEC's website to access the file

Aerosol Printing and Flash Sintering of Conformal Conductors on 3D Nonplanar Surfaces

Printing techniques have been extensively studied as a promising route towards large-scale, low-cost and high-throughput manufacturing process for electronic devices. With the recently emerging applications in wearable electronics and customizable conformal electronics, it calls for the necessity to develop printed electronics that function on complex, 3D nonplanar architectures. In this study, aerosol printing and flash sintering of conformal conductors on nonplanar surfaces are demonstrated. Various printed patterns are fabricated by aerosol printing of conductive ink by copper nanoparticles (Cu NPs) on both planar and nonplanar surfaces. Pulsed flash light introduces rapid sintering of the printed Cu patterns in the ambient environment. For the nonplanar patterns, a back reflector is utilized to improve the uniformity of sintering. As a result, highly conductive customizable nonplanar Cu patterns with conductivity at 10%-12% of that of bulk Cu are obtained. Effects of different sintering conditions, including sintering voltage and mounting distance on the conductivity of sintered patterns are studied. For nonplanar patterns, conductivity values at different localized spots on the nonplanar rod are also investigated to evaluate the uniformity of nonplanar sintering. The processes of aerosol printing and flash sintering have provided a facile manufacturing route for conformal conductors on arbitrary nonplanar objects

Customizable Nonplanar Printing of Lithium-Ion Batteries

Lithium-ion batteries (LIBs) are widely used in consumer electronics due to their rechargeability and high energy density. Commercial LIBs are fabricated in fixed geometries such as cylinder, coin, and pouch. However, for specialized applications such as wearable electronics and on-device power systems, customizable LIBs with arbitrary geometry on three-dimensional (3D) structures need to be developed. For this purpose, aerosol printing is uniquely suitable due to its flexible working distance, allowing deposition on nonplanar substrates with multiscale surface topologies. Aerosol printing of LiFePO4 cathodes and Li4Ti5O12 anodes for LIBs is presented. Electrodes with an arbitrary geometry, tailorable thickness and on nonplanar substrates can be realized. The highest areal capacity achieved is ≈7.1 mAh cm-2, which is at least twice that of conventional electrodes. Furthermore, to package the printed electrodes, 3D enclosures are fabricated via fused deposition modeling of polyvinylidene fluoride. The printed electrodes packaged in 3D enclosures exhibit 78.4% capacity retention after 30 cycles. With the two additive manufacturing processes, customizable LIBs on targeted objects can be realized. A nonplanar LIB conformably covering the edge of a block with specific capacity of 135 mAh g-1 is demonstrated