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Energy Technologies: MMSE

Active projects in Materials & Mechanical Systems Engineering (MMSE) with applications for energy technologies:

Alloys for high-temperature power applications that are strong, corrosion resistant and economically viable are critical for the operation of power generation plants at higher temperatures. Operation at high temperature can lead to energy conversion efficiencies of >50%, which will not only reduce running costs, but also extend the lifetime of fossil fuels and/or reduce the carbon footprint of the plants. In this project, iron-based austenitic steels strengthened with Laves phase precipitates, and alloyed with aluminum for improved oxidation resistance, e.g. Fe-20Cr-20Ni-2Nb-5Al (at.%), are being studied. The project aims to generate finer, higher volume fractions of Laves precipitates in the matrix by using enhanced nucleation on dislocations introduced through cold work. These precipitates will increase the strength and also minimize the formation of grain boundary precipitates, thus retarding the growth of the latter and extending the creep life of the alloy. The precipitates are being characterized after both static ageing and creep using transmission electron microscopy (TEM), and TEM hot in-situ straining experiments are being used to examine the deformation mechanisms.
(Faculty contact: I. Baker)

Ice mechanics research is conducted to determine physical processes that underlie brittle failure on scales large (Arctic) and small (laboratory). The current goal is to relate failure of the arctic sea ice cover and fracture during ice interaction with off-shore engineered structures to processes such as wing-crack and comb-crack formation and the development of shear faults. The underlying hypothesis is that brittle compressive failure is a scale-independent process driven by intermittent frictional sliding and stable crack growth. The hypothesis is applicable to other brittle materials as well, such as ceramics, rock, and minerals.
(Faculty contact: Schulson)

High-power density magnetic components for dc-dc power converters are being developed using microfabrication techniques. The small size and fast response time of these high-frequency converters will make them advantageous for power delivery to low-voltage microprocessors and other digital systems.
(Faculty contact: Sullivan)

High-strength quaternary alloys with ultrafine microstructures result from a combination of spinodal decomposition and atomic ordering transformations. Research aims to relate the progression of these transformations to bulk properties such as strength, hardness, and ferromagnetism. Such high-strength low-density alloys would have many industrial and aerospace applications. Some of this work is performed in collaboration with Oak Ridge National Laboratory and also the University of Sydney.
(Faculty contact: I. Baker)

Intermetallic compounds show great promise as structural materials for high-temperature applications because of their high strength and resistance to oxidation and corrosion. However, many intermetallic compounds are brittle at ambient temperatures. Current research aims to understand the causes of brittle fracture and to observe the yield anomaly in these compounds.
(Faculty contact: I. Baker)

Magnetic alternatives to conventional CMOS technologies are being investigated—in particular, the use of nanomagnetic ring elements as logic gates and memory elements. These systems retain information in the absence of power, potentially allowing computational devices to be powered up and down without rebooting.
(Faculty contact: Gibson)

Magnetohydrodynamics (MHD) is a combination of fluid mechanics and electromagnetics concerned with the motion of electrically-conducting fluids and gases in the presence of a magnetic field. Examples of technical applications are electric power generation, electromagnetic pumping and propulsion as well as control of moving molten metals. MHD research at Thayer School is concerned with the high-speed flow of tenuous, ionized gas from the Sun past the Earth's magnetic field. The research is fundamental in nature but also contributes to the development of a national space-weather forecasting capability. This capability is important for the safe operation of manned spacecraft and a variety of communications, global-positioning, and defense satellite systems, as well as for protection against geomagnetically-induced electric power outages on Earth.
(Faculty contact: Lotko)

Microstructural characterization of snow and ice cores is crucial to understanding the effects of microstructure and impurities in ice. Researchers here pioneered a way to use the scanning electron microscope (SEM) to study the impurities in uncoated ice and have recently developed a way to gather precise orientation information from ice using electron back scatter patterns (EBSP). Dartmouth engineers are also investigating the type and location of impurities in polar ice cores using a confocal Raman microscope. These efforts will further scientists' understanding of the effect of microstructural properties of ice on the mechanical behavior of ice sheets and glaciers and help paleoclimatologists better interpret the ice core record.
(Faculty contact: I. Baker)

Microstructure and mechanical behavior of FeNiMnAl eutectic alloys is being studied to understand the deformation mechanisms controlling the strength and ductility of a recently-discovered, high-strength, ductile, eutectic FeNiMnAl alloy, Fe30Ni20Mn35Al15, that consists of f.c.c. and B2 (ordered b.c.c.) phases and to model the yield strength and ductility either by using existing models or by developing new models. The work involves mechanical testing and microstructural characterization using a combination of state-of-the-art techniques including transmission electron microscopy (TEM) including convergent beam electron diffraction and energy dispersive x-ray spectroscopy; a high resolution TEM; and atom probe tomography. These will provide information on the lamellar spacing and morphology, microchemistry, lattice parameters, orientation relationships between the f.c.c. and B2 phases, interface strains and interface structure.
(Faculty contact: I. Baker)

Nanostructured magnetic materials research involves development of new magnetic alloy compositions via casting, and processing them using a variety of techniques including mechanical alloying, sputtering, and electroplating. Applications of these magnetic materials will range from on-chip transformers to high-temperature turbine power generators. The clinical applications of using magnetic nanoparticles are also under investigation.
(Faculty contacts: I. Baker, Sullivan)

Pulse electro-thermal de-icing (PETD) is a new method of ice removal and prevention that uses short pulses of electricity applied directly to an ice-material interface. PETD uses a thin, electrically-conductive film applied to the substrate. The film is then heated with a milliseconds-long pulse of electricity. Because only a micrometer-thin layer of ice is melted, PETD achieves nearly perfect efficiency even in extreme cold. Regular pulsing can keep surfaces consistently ice-free while maintaining low overall power consumption. Research is ongoing for the extensive applications of PETD such as de-icing of airplanes, ships, refrigeration systems, windshields, power lines, bridges and buildings, roads and walkways, and windmill turbines.
(Faculty contact: Petrenko)

See also Victor Petrenko's Ice Engineering (summary)

Thermal spraying involves particles less than 100 microns in diameter. Particles are accelerated and heated while exposed to a supersonic hot gas stream forming a gas dynamic shock upstream of each particle. Current research aims to solve the heat transfer in this complex flow with computational fluid dynamics.
(Faculty contact: Richter)

Wear of nanocrystalline metals and alloys is being studied to understand the wear mechanisms and to model accurately wear rate as a function of grain size. To this end, bulk nanocrystalline Al, Al-Si and Mg will be produced by equal channel angular extrusion of milled powders. We will also produce bimodal grain structures consisting of nanocrystalline and conventionally-grained material, which we expect will have high hardness yet good ductility. The microstructures will be characterized using a TEM and XRD. Such bulk nanocrystalline materials should not suffer from the difficulties of interpreting wear data that occur for coatings and modified surface layers where the grain size and strain often vary throughout the layers.
(Faculty contact: I. Baker, Kennedy)