A HIGH ENTROPY ALLOY FOR ADVANCED ULTRASUPER CRITICAL STEAM TURBINES
Title
A HIGH ENTROPY ALLOY FOR ADVANCED ULTRASUPER CRITICAL STEAM TURBINES
ICCI Project ID
15/ER-11
Investigator
Hattrick-Simpers
Institution
University of South Carolina
ICCI Abstract
Due to the new Environmental Protection Agency guidelines for the reduction of CO2 emissions there is renewed interest in the development of Ultra-Super Critical (USC) steam turbines. Unfortunately the higher temperatures and pressures required for USC units compared to conventional turbines precludes the use of current state-of-the-art alloys and thus new materials must be developed in a timely manner. The recent development of a novel alloying concept in which the center of the multi-component phase diagram is searched for stable, equiatomic, and single-phase alloys offers great potential for the next generation of turbine materials. Termed \"high entropy alloys\" these materials are stabilized at high temperatures by large entropic contributions to their Gibb\'s free energy. These alloys have been previously reported to have superior high temperature mechanical properties, are known to exhibit high temperature corrosion resistance in air, and have the sluggish diffusion rates required to inhibit the growth of secondary phases. Although this new alloying method holds great promise for the development of USC turbines, a large composition-processing-performance parameter space must be rapidly explored to identify promising alloys with appropriate phase stability and oxidation resistance at temperatures of up to 850°C.
We propose to utilize our established expertise in the use of high-throughput methodologies to discover new stable and oxidation resistant high-entropy alloys for use in USC turbine environments. In the high-throughput approach to materials science, thousands of samples are synthesized simultaneously, processed, and then screened in parallel for their figure of merit. This permits one to quickly explore composition-processing-microstructure-performance space to identify \"lead\" materials for more detailed exploration. This project will build upon on our previous successes using this approach to identify novel oxidation resistant materials for high temperature turbines and dramatically increase the rate at which novel HEAs are discovered.
Specifically, we will use thin-film continuous composition spread techniques to deposit a series of high entropy alloys of the form AlxCuyMo1-x-yTiVFeNiZr and systematically screen them for their phase stability and ability to resist oxidation. This approach has previously been validated to provide high-quality materials \"leads\" for bulk structural material systems such as shape memory alloys, magnetostrictive materials, and superalloys. We will employ state-of-the-art in situ characterization techniques such as high-throughput synchrotron micro-diffraction at the Stanford Linear Accelerator and Collider to investigate the role of composition and processing on the stability of the high entropy phase and its tendency to phase segregate into nano-sized precipitates. A combination of in situ and ex situ diffraction and spectroscopy will then be used to monitor the oxidation of the most interesting alloy systems, including the effect of oxidation on the stability of the high entropy phase and its ability to form a protective oxide at elevated temperature.
This study will screens thousands of different potential high entropy alloys in one year generating a treasure-trove of knowledge regarding composition-processing-property relationships in this fascinating new field of alloy science. By the end of the year, we will recommend three to four potential alloys for bulk fabrication, mechanical testing, and long term oxidation studies.
We propose to utilize our established expertise in the use of high-throughput methodologies to discover new stable and oxidation resistant high-entropy alloys for use in USC turbine environments. In the high-throughput approach to materials science, thousands of samples are synthesized simultaneously, processed, and then screened in parallel for their figure of merit. This permits one to quickly explore composition-processing-microstructure-performance space to identify \"lead\" materials for more detailed exploration. This project will build upon on our previous successes using this approach to identify novel oxidation resistant materials for high temperature turbines and dramatically increase the rate at which novel HEAs are discovered.
Specifically, we will use thin-film continuous composition spread techniques to deposit a series of high entropy alloys of the form AlxCuyMo1-x-yTiVFeNiZr and systematically screen them for their phase stability and ability to resist oxidation. This approach has previously been validated to provide high-quality materials \"leads\" for bulk structural material systems such as shape memory alloys, magnetostrictive materials, and superalloys. We will employ state-of-the-art in situ characterization techniques such as high-throughput synchrotron micro-diffraction at the Stanford Linear Accelerator and Collider to investigate the role of composition and processing on the stability of the high entropy phase and its tendency to phase segregate into nano-sized precipitates. A combination of in situ and ex situ diffraction and spectroscopy will then be used to monitor the oxidation of the most interesting alloy systems, including the effect of oxidation on the stability of the high entropy phase and its ability to form a protective oxide at elevated temperature.
This study will screens thousands of different potential high entropy alloys in one year generating a treasure-trove of knowledge regarding composition-processing-property relationships in this fascinating new field of alloy science. By the end of the year, we will recommend three to four potential alloys for bulk fabrication, mechanical testing, and long term oxidation studies.
Start Date
3/1/2015
End Date
2/29/2016
Year Funded
2015
Manager
Francois Botha
Collection
Citation
“A HIGH ENTROPY ALLOY FOR ADVANCED ULTRASUPER CRITICAL STEAM TURBINES,” ICCI Reports, accessed May 20, 2024, https://isgswikis.web.illinois.edu/icci_reports/items/show/845.