Principles of equal-channel angular pressing as a processing tool for grain refinement

Metallic alloys

A conservative level set method for two phase flow II

It is well known that plastic deformation induced by conventional forming methodssuch as rolling, drawing or extrusion can significantly increase the strength of metalsHowever, this increase is usually accompanied by a loss of ductility. For example, Fig.1 shows that with increasing plastic deformation, the yield strength of Cu and Almonotonically increases while their elongation to failure (ductility) decreases. Thesame trend is also true for other metals and alloys. Here we report an extraordinarycombination of high strength and high ductility produced in metals subject to severeplastic deformation (SPD). We believe that this unusual mechanical behavior is causedby the unique nanostructures generated by SPD processing. The combination ofultrafine grain size and high-density dislocations appears to enable deformation by newmechanisms. This work demonstrates the possibility of tailoring the microstructures ofmetals and alloys by SPD to obtain both high strength and high ductility. Materialswith such desirable mechanical properties are very attractive for advanced structuralapplications.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0884291400060143

Paradox of strength and ductility in metals processed by severe plastic deformation

Size dependence of nanostructures: Impact of bond order deficiency

General physical and chemical constants X-ray analysis of metallic material Crystallography Crystal chemistry Metallurgically important minerals Thermochemical data Physical properties of molton salts Metallography Equilibrium diagrams Gas-metal systems Diffusion in metals General physical properties Elastic properties, damping capacity and shape memory alloys Temperature measurement and thermoelectric properties Radiating properties of metals Electron emission Electrical properties Magnetic materials and their properties Mechanical testing Mechanical properties of metals and alloys Sintered materials Lubricants Friction and wear Casting alloys and foundry data Engineering ceramics and refractory materials Fuels Heat treatment Metal cutting and forming Corrosion Electroplating and metal finishing Welding Soldering and brazing Vapour deposited coatings and thermal spraying Superplasticity Metal-matrix composites Non-conventional and emerging metallic minerals modelling and simulation supporting technologies for the processing of metals and alloys.

Smithells metals reference book

Creep-fatigue testing of alloy 617 was performed in air, vacuum, and purified Ar environments at 1000 °C. Tests were performed in axial strain control at total strain ranges of 0.3% and 1.0% (fully reversed) with hold times at maximum tensile strain ranging from 0 to 1800 s. Introduction of a tensile hold period led to reduced creep-fatigue life at both strain ranges in all environments; the effect was greater at 0.3% than 1.0%. The hold time effect clearly saturated for tests at 1.0% strain range; the behavior at 0.3% was not clear. Decarburization occurred in specimens tested in vacuum and purified Ar, but not in air. Although fatigue lives were longer in the inert environments than in air for most test conditions, quantitative assessment of the differences was not possible because cracking frequently did not occur before test termination due to load drop for tests in inert environment. Cavitation damage was observed for tests with tensile hold periods in all environments.

Creep-fatigue-environment interactions in INCONEL 617

FeAl and Mo–Si–B intermetallic coatings prepared by thermal spraying

The microstructure and state of stress present in Fe3Al coatings produced by high velocity oxygen fuel (HVOF) thermal spraying in air at varying particle velocities were characterized using metallography, curvature measurements, x-ray analysis, and microhardness measurements. Sound coatings were produced for all conditions. The microstructures of coatings prepared at higher velocities showed fewer unmelted particles and a greater extent of deformation. Residual stresses in the coatings were compressive and varied from nearly zero at the lowest velocity to approximately −450 MPa at the highest velocity. X-ray line broadening analyses revealed a corresponding increase in the extent of cold work present in the coating, which was also reflected in increased microhardness. Values of mean coefficient of thermal expansion obtained for assprayed coatings using x-ray analysis were significantly lower than those for powder and bulk alloy.

Microstructure and stresses in HVOF sprayed iron aluminide coatings

The U.S. and other countries address major challenges related to energy security and the environmental impacts of fossil fuels. Solutions to these issues include carbon-free electricity generation and hydrogen production for fuel cell car, fertilizer synthesis, petroleum refining, and other applications. The Very High Temperature Gas Reactor (HTGR) has been recognized as a promising technology for high efficiency electricity generation and high temperature process heat applications. Therefore, the U.S. needs to make the HTGR intrinsically safe and proliferation-resistant. The U.S. and the world, however, must still overcome certain technical issues and the cost barrier before it can be built in the U.S. The establishment of a nuclear power cost goal of 3.3 cents/kWh is desirable in order to compete with fossil combined-cycle, gas turbine power generation. This goal requires approximately a 30% reduction in power cost for state-of-the-art nuclear plants. It has been demonstrated that this large cost differential can be overcome only by technology improvements that lead to a combination of better efficiency and more compatible reactor materials. The objectives of this research are (1) to develop a supercritical carbon dioxide Brayton cycle in the secondary power conversion side that can be applied to some Generation-IV reactors such as the HTGR and supercritical water reactor, (2) to improve the plant net efficiency by using the carbon dioxide Brayton cycle, and (3) to test material compatibility at high temperatures and pressures. The reduced volumetric flow rate of carbon dioxide due to higher density compared to helium will reduce compression work, which eventually increase turbine work enhancing the plant net efficiency.

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Terry C. Totemeier

Papers

Smithells metals reference book

Creep-fatigue-environment interactions in INCONEL 617

FeAl and Mo–Si–B intermetallic coatings prepared by thermal spraying

Microstructure and stresses in HVOF sprayed iron aluminide coatings

Development of a Supercritical Carbon Dioxide Brayton Cycle: Improving PBR Efficiency and Testing Material Compatibility - 2004 Annual Report