Researchers at Idaho National Laboratory, Idaho Falls, announce that they have developed a heat treatment process that enables superalloys to withstand high heat more than six times longer than an untreated counterpart, extending useful life by thousands of hours in applications such as nuclear reactors.
“We came up with a way to make a superalloy that is much more resistant to heat-related failures. This could be useful in electricity generators and elsewhere,” says Subhashish Meher, an INL materials scientist. He was lead author of a new Science Advances paper describing the research.
INL scientists have been studying nickel-base superalloys, which are useful for electricity-generating turbines and high-temperature nuclear reactor components. Previous research had shown that performance can be improved if the material structure of the superalloy repeats in some way from very small sizes to very large, like a box within a box within a box.
This is called a hierarchical microstructure. In a superalloy, it consists of a metallic matrix with precipitates, regions where the composition of the mixture differs from the rest of the metal. Embedded within the precipitates are still finer-scale particles that are the same composition as the matrix outside the precipitates — conceptually like nested boxes.
Dr. Meher and his coauthors found that with the right recipe of heating and cooling, they could make the precipitates two or more times larger than would be the case otherwise, thereby creating the heat-resistant microstructure.
These larger precipitates last longer when subjected to extreme heat. Moreover, computer simulation studies suggest that the superalloy can resist heat-induced failure for 20,000 hours, compared to about 3,000 hours normally.
One application could be electrical generators that last much longer because the superalloy structures would be tougher. What’s more, INL scientists may now be able to come up with a procedure that can be applied to other superalloys. So, it may be possible to adjust a superalloy’s strength, heat tolerance, or other properties to enhance its use in a particular application.
https://www.inl.gov/article/treated-superalloys-demonstrate-unprecedented-heat-resistance/
