Intermetallic compounds (metallic materials composed of definite proportions of two or more elemental metals) resist oxidation and remain strong at high temperatures, making them useful for energy technologies. But until recently, these compounds were too brittle to be fabricated into conventional shapes using traditional methods. In 1981, Oak Ridge National Laboratory started a program to increase understanding of intermetallic compounds and develop scientific principles for improving their properties. Following a Japanese report suggesting that small amounts of boron made a nickel aluminide compound more ductile, Oak Ridge researchers led by Chain T. Liu determined the mechanism behind the change. They also showed that iron aluminides are intrinsically ductile at ambient temperatures and that brittleness is caused by moisture in the air. Quantum mechanical calculations demonstrated a mechanism that reduced the cohesive strength of atomic layers in these alloys by 70 percent, a discovery that led to new and improved alloy designs. Liu was awarded the 2001 Acta Metallurgica Gold Metal for his outstanding leadership and achievements in this research. The Office of Science then worked with DOE offices of Energy Efficiency and Fossil Energy to fund a research program on intermetallic compounds, an effort that has won three R&D 100 awards from R&D Magazine recognizing significant new technologies, and has resulted in more than 16 patents and 12 licenses.

Scientific Impact: Materials and processing research at Oak Ridge has increased scientific understanding of intermetallic compounds. This work overcame the brittleness problem and improved manufacturability, thus making it practical to use nickel and iron aluminides for high temperature engineering applications.

Social Impact: This research has helped to improve product quality and reduce costs. For instance, the use of nickel-aluminide dies for the hot forging process improves the quality of steel parts in automobiles, and iron-aluminide filters used to remove ash particles during coal gasification reduce costs and resist the corrosiveness of hydrogen sulfide in the gas stream.

Reference: Pope, D. P., C, T. Liu, S. H. Whang, and M. Yamaguchi, eds., High Temperature Intermetallics, Elsevier, New York (1997).

URL: http://www.ornl.gov/bes/BES/abad/alloying.htm
http://www.ornl.gov/bes/BES/abad/staff6/liu.htm

Technical Contact: Don Freeburn, Office of Basic Energy Sciences, 301-903-3156

Press Contact: Jeff Sherwood, DOE Office of Public Affairs, 202-586-5806

SC-Funding Office: Office of Basic Energy Sciences