For release: Oct. 30, 2000

Contacts:
Brian Gleeson, Process Science Initiative, (515) 294-5606
Larry Jones, Materials Preparation Center, (515) 294-5236
Susan Dieterle, Public Affairs, (515) 294-1405

TAKING THE INITIATIVE

Ames Laboratory facility leads effort to better understand how materials are processed

AMES, Iowa -- Like cooks on tight budgets, most materials scientists can't afford to experiment with new "recipes." They follow tried-and-true methods for melting, cooling and shaping various materials into usable forms even though the science behind those methods isn't always fully understood.

But a one-of-a-kind effort is underway at the Materials Preparation Center, part of the U.S. Department of Energy's Ames Laboratory, to delve more deeply into the mysteries of processing science -- the methods by which metals, alloys, polymers and ceramics are synthesized in order to give them specific properties. By turning the MPC into a test kitchen of sorts, Ames Lab scientists hope to better understand existing processing methods and develop recipes, or techniques, for making advanced materials for future technologies.

A new program called the Process Science Initiative offers a limited pool of competitive funding for two types of materials-processing projects: those that lead to an improved fundamental understanding of existing processing techniques and those that explore new techniques for producing novel materials.

The Department of Energy provides funds for the PSI program, and research facilities are provided by the MPC and Ames Laboratory. The MPC is a designated DOE national user facility that specializes in preparing small samples of high-purity, novel materials that aren't available from commercial sources.

Brian Gleeson, an assistant professor of materials science and engineering at Iowa State University, serves as PSI program manager. He said it's critical that scientists understand what happens to a material when it goes from a liquid state to a solid state because most metals and alloys are made of tiny crystals. The way in which the liquid crystallizes to form the microstructure of the solid determines the material's properties, such as its strength and formability. Subsequent secondary processing, such as rolling or extruding, also affects a material's properties.

"In a lot of the recent research, we've focused heavily on the properties of materials without really understanding how we arrived at, or control, the microstructure," Gleeson said. "Materials scientists see the need for research that will give them this type of information."

Larry Jones, director of the Materials Preparation Center, said determining how to synthesize metals and alloys is a difficult task. "The materials we're dealing with today often have high melting points, or they may easily pick up impurities from the crucibles we melt them in," he said. "And they may need to be cooled in a very regimented way to produce the desired microstructure."

With most complex materials, scientists have a limited understanding of what happens to the metal or alloy while it's being processed. "You have to know the conditions -- such as the temperatures, the forces and the amount of deformation -- affecting that material during processing," Jones said. "Accurately measuring those parameters is not easy when you're dealing with temperatures of 1,800 C (3,272 F), which is an aggressive thermal environment."

The PSI program is the only known initiative to focus specifically on improving the science of materials processing, Gleeson said. In fiscal year 2000, four projects received $141,000 in PSI funds. The Department of Energy authorized an increase of the PSI budget to $250,000 for the current fiscal year, which began Oct. 1. Four projects have already been selected to share approximately $175,000 of those funds, with the remaining $75,000 to be allocated later in the year.

Among the projects receiving PSI funds is one in which Ames Lab scientists are studying the properties of solid-liquid interfaces. "In alloy systems, there's a range of solidification where the liquid and solid phases of the material coexist," Gleeson said. "It's the coexistence of the solid and the liquid that really sets the stage for the final product."

The scientists built a rig that enables them to reach and maintain the liquid/solid coexistence and then measure the properties of the interface between the two phases. "This is very fundamental knowledge that could be applicable to a range of other alloy systems," Gleeson said. (Click here for a list of all PSI-funded projects.)

Another project that received funding for the current year involves synthesizing and characterizing polymer gels that respond to pH or temperature changes. The goal is to develop polymer gels that would either swell or contract in response to specific pH or temperature changes. "This is a formidable materials-synthesis challenge, but success would be of both fundamental and practical significance," Gleeson said. One application for such polymers would be in vivo drug delivery (i.e., a polymer and a drug would be combined in such a way to release the drug in the body in a predesigned manner).

Ames Laboratory is operated for the Department of Energy by Iowa State University. The Lab conducts research into various areas of national concern, including energy resources, high-speed computer design, environmental cleanup and restoration, and the synthesis and study of new materials.

One of the DOE's primary missions is to engage in research that leads to the development of materials that improve the efficiency, economy, environmental acceptability and safety of energy sources.

In fiscal year 2000, $141,000 in Process Science Initiative funding was allocated to:

• A team of Ames Lab scientists led by Matt Kramer, $28,000 to explore the rapid solidification of metals. The team studied the melt-spinning technique in which liquid metal is dropped onto a spinning wheel that forms the metal into a thin ribbon. "We don't clearly know what happens from the pouring of the metal to the point of its contact with the wheel," said PSI program manager Brian Gleeson. "But what happens during this sequence affects the properties of the metal." The team used high-speed photography and temperature measurements to better understand what takes place.
• Ames Lab scientist Dan Sordelet and David Cann, an ISU assistant professor of materials science and engineering, $35,000 to study a possible method of producing zirconium-tungstate, a ceramic material, that could then be blended with a metal to form a composite. Gleeson said zirconium-tungstate is unique because it tends to contract when heated, rather than expanding as most materials do. By combining zirconium-tungstate with varying amounts of a metal that expands, researchers could "tune" the composite material's coefficient of thermal expansion.
• Ames Lab senior metallurgist Karl Gschneidner Jr., $35,000 to study how deformation processing affects a compound with an ordered crystal structure identical to that of cesium-chloride. "This is a certain type of crystal structure that is inherently brittle, but Karl is looking at a type of alloy that shows a surprising amount of ductility, which means it's easier to deform," Gleeson said. "This research could have consequences for deformation processing of brittle materials, such as rolling the material into a sheet or making it into a tube."
• An Ames Lab team led by associate scientist Ralph Napolitano, $43,000 to study the properties of solid-liquid interfaces. "In alloy systems, there's a range of solidification where the liquid and solid phases of the material coexist," Gleeson said. "It's the coexistence of the solid and the liquid that really sets the stage for the final product." The team built a rig that enables them to reach and maintain the liquid/solid coexistence and measure the properties of the interface between the phases.

Of the $250,000 allocated for fiscal year 2001, about $175,000* has been awarded to:

• The team led by Kramer, $40,000 to expand on the project that received PSI funds the previous year. The group will measure both the rapid and directional solidification processes in a neodymium-iron-boron alloy, which is used in powerful magnets. Understanding how the material solidifies could enable scientists to optimize the performance of the magnetic materials.
• The team led by Napolitano, $63,000 to continue studying the properties of solid-liquid interfaces -- a project that also was funded last year. Among other plans for the coming year, the team will work to extend a theoretical model of crystal-shape development from a two-dimensional to a three-dimensional calculation.
• Surya Mallapragada, an Iowa State University associate professor of chemical engineering, $35,000 to synthesize and characterize polymer gels that respond to pH or temperature changes. Her goal is to develop polymer gels that would either swell or contract in response to specific pH or temperature changes. "This is a formidable materials-synthesis challenge, but success would be of both fundamental and practical significance," Gleeson said. One application for such polymers would be in-vivo drug delivery (i.e., a polymer and a drug would be combined in such a way to release the drug in the body in a predesigned manner).
• Richard Figliola, a professor of mechanical engineering at Clemson University, $36,000 to characterize the flow of high-pressure gas atomizers; the Ames Lab collaborator is Iver Anderson, director of the Metallurgy and Ceramics program. Figliola and Anderson will make direct measurements of this process under actual operating conditions to correct a systematic error in the existing numerical model. Refining the model will improve the ability of scientists and manufacturers to control the properties of the metal powders produced with this process.

* Budgets for the FY01 projects are still being finalized. Additionally, the remainder of the funding -- approximately $75,000 -- is being reserved for allocation later in the year.

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