Materials R&D trends in theUnited States

I will present in this lecture a broad overview of materials R&D trends in the United States as I see them, and will present a few examples, mostly from my own experience. Of course, the field is so broad and diverse that only a limited number of examples will have to suffice to illustrate the main points. Federal funding of materials research in the United States is somewhat over a billion dollars per year

Alloy undercooling experiments

The research accomplished during 1995 can be organized into three parts. The first task involves analyzing the results of microgravity experiments carried out using TEMPUS hardware during the IML-2 mission on STS-65. The second part was to finalize ground-based experimentation which supported the above flight sample analysis. The final part was to provide technical support for post-flight mission activities specifically aimed at improving TEMPUS performance for potential future missions

The alloy undercooling experiment on the Columbia STA 61-C space shuttle mission

An Alloy Undercooling experiment was performed in an electromagnetic levitator during the Columbia STS 61-C mission in January 1986. One eutectic nickel-tin alloy specimen was partially processed before an equipment failure terminated the experiment. Examination of the specimen showed evidence of undercooling and some unusual microstructural features

Factors affecting segregation in the controlled solidification of aluminum-copper and aluminum-zinc alloys

Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Metallurgy, 1954.Includes bibliographical references (leaves ).by Merton C. Flemings, Jr.Sc.D

Bimodal Casting Process of Eco-Mg Series Alloys by Vertical High-Speed Press Machine

Ultimate advancements in non-flammable magnesium alloys (the so-called Eco-Mg alloys series, acronym of Environment Conscious Magnesium) have been recently achieved. Preliminary laboratory tests have been already confirmed safe window parameters (i.e. exposure time and maximum melting temperature) for processing Eco-Mg AZ91D-1.5CaO alloy in full liquid state. Further project challenge has been now completed; Eco-Mg samples have been realized in special novel pre-industrial vertical 4-column press machine, designed and constructed for processing Eco-Mg series alloys in air by two routes, by high-pressure die casting and by semisolid state injection. An external rotating stirrer finely controlled in temperature, and rotating velocity completes the semisolid process route, allowing Eco-Mg alloy remaining below flame-ignition temperature. Microstructure investigation on samples produced in both high-pressure die casting and semisolid state patterns has been performed. To date, such a bimodal pilot line is thought to introduce affordable industrial way e for producing near-net-shape Mg parts

Flight Planning for the International Space Station - Levitation Observation of Dendrite Evolution in Steel Ternary Alloy Rapid Solidification (LODESTARS)

During rapid solidification, a molten sample is cooled below its equilibrium solidification temperature to form a metastable liquid. Once nucleation is initiated, growth of the solid phase proceeds and can be seen as a sudden rise in temperature. The heat of fusion is rejected ahead of the growing dendrites into the undercooled liquid in a process known as recalescence. Fe-Cr-Ni alloys may form several equilibrium phases and the hypoeutectic alloys, with compositions near the commercially important 316 stainless steel alloy, are observed to solidify by way of a two-step process known as double recalescence. During double recalescence, the first temperature rise is associated with formation of the metastable ferritic solid phase with subsequent conversion to the stable austenitic phase during the second temperature rise. Selection of which phase grows into the undercooled melt during primary solidification may be accomplished by choice of the appropriate nucleation trigger material or by control of the processing parameters during rapid solidification. Due to the highly reactive nature of the molten sample material and in order to avoid contamination of the undercooled melt, a containerless electromagnetic levitation (EML) processing technique is used. In ground-based EML, the same forces that support the weight of the sample against gravity also drive convection in the liquid sample. However, in microgravity, the force required to position the sample is greatly reduced, so convection may be controlled over a wide range of internal flows. Space Shuttle experiments have shown that the double recalescence behavior of Fe-Cr-Ni alloys changes between ground and space EML experiments. This program is aimed at understanding how melt convection influences phase selection and the evolution of rapid solidification microstructures