Title : Effect of alloying elements content on mechanical properties and oxidation behavior in dry and wet atmopshere of NiCoCrAlFe-X high entropy alloys
Abstract:
A constant requirement to decrease greenhouse gas emissions in combination with the desire to increase gas turbine efficiency results in a continuous trend to increase the operating temperature of gas turbines. This increase is determined mainly by the Carnot cycle, according to which the increase of the temperature in the engine results in an increase in the gas turbine efficiency. This in turn will result in lower fuel consumption, and higher combustion temperature shall result in lower pollution releasing. Moreover, there is a strong trend to use hydrogen as an alternative and clean fuel. However, using hydrogen or hydrogen-rich fuel results in a higher combustion temperature as well as an increase in the water vapor content in the exhaust gases. Modern materials used today are mainly Ni-based superalloys. However, the use of Ni-base alloys faces their limits. Moreover, studies on the effect of water vapor on oxidation kinetics showed a worsening of the oxidation behavior of Ni-based alloys in an atmosphere containing water vapor. Therefore, a new brand of materials is demanded to be used in gas turbines operated with hydrogen-rich fuel. High-entropy alloys (HEA) seem to be very promising materials to replace commonly used Ni-based alloys. HEA’s are the group of materials consisting of at least five main equiatomic elements. These alloys can be doped by other elements in amounts less than 5 at. % in total. Thus, in the present study, NiCoCrAlFe-X alloys are studied in terms of mechanical properties and oxidation behavior during exposure to dry and wet atmospheres. NiCoCrAlFe-X alloys are doped with e.g. W or Mo in the amount varying from 1-5 at.%. The effect of alloying element concentration on mechanical properties and oxidation resistance in dry and wet atmospheres will be shown and discussed.
Audience take away Notes:
- The presented results will surely expand the knowledge of the audience about the high entropy alloys, especially exposed to atmosphere containing water vapor
- The audience can clearly compare the results obtained on studied HEA’s with state of the art Ni-base alloys and find the proper field of application of HEA’s
- The audience can learn about the different oxidation mechanisms during exposure in dry and wet atmosphere
