Al-Ce-Mg alloys enable easier casting, higher temperatures for engine parts
June 07, 2016
Source: ASM International
Researchers from Oak Ridge National Laboratory and partners Lawrence Livermore National Laboratory and Eck Industries announce that they have developed aluminum-cerium alloys that are lower in cost, easier to cast, and more resistant to high temperatures than existing products. The most promising alloys are ternary compositions of aluminum, cerium, and magnesium. For example, room-temperature strengths in the as-cast condition of Al-8Ce-10Mg are 30 ksi tensile and 23 ksi yield. At 500°F, they are 20 ksi tensile and 18 ksi yield. The key to its high-temperature function is an aluminum-cerium intermetallic that forms during melting and casting. This intermetallic melts at temperatures above 2000°F.
"Most alloys with exceptional properties are more difficult to cast," says David Weiss, vice president for engineering and R&D at Eck Industries. "But the aluminum-cerium system has equivalent casting characteristics to the aluminum-silicon alloys." The photo shows an aluminum-cerium-magnesium engine part cast by Eck Industries.
The team is working as part of the Critical Materials Institute at the Ames Laboratory in Iowa. The purpose of the institute is to increase the availability of rare earth metals and other materials critical for U.S. energy security. Aluminum-cerium alloys promise to boost domestic rare earth mining by increasing the demand and, eventually, the value of cerium.
One problem is that cerium accounts for up to half of the rare earth content of many rare earth ores, but it has limited large-volume applications. The most common rare earth ore in the United States, in fact, contains three times more cerium than neodymium and 500 times more cerium than dysprosium. However, if the new alloys were to find a place in internal combustion engines, they could quickly transform cerium from an inconvenient byproduct of rare earth mining to a valuable product in itself. A 1% penetration into the market for aluminum alloys would translate to 3000 tons of cerium.
Industries and Applications | Automobiles and Ground Transportation
Materials Processing and Treatment | Casting
Metals and Alloys | Aluminum
Metals and Alloys | Magnesium