Searching the Fe-Mn-Ni-Al-Cr Composition Space for Materials with High Strength at High Temperature for Use as Solar Absorbers in Concentrating Solar Thermal Plants

In order to increase the maximum efficiency of concentrating solar thermal plants, higher operating temperatures are necessary. One issue that arises when attempting to increase plant operating temperatures is that of finding a proper material for the absorber tube. It must be capable of having a long service life with acceptable levels of creep, tolerance to day/night thermal cycling, and resistance to degradation from the working fluid. The high entropy alloy (HEA) Fe_28.2Mn_18.8Ni_32.9Al_14.1Cr₆ has shown some promise for this use [1]. We will explore the composition space of this alloy to further optimize it for use as a solar absorber. To investigate any significant fraction of the 5-component composition experimentally is practically impossible. From density functional theory (DFT), we will perform a cluster expansion for the system and use this to account for disordered phases and temperature effects to explore the phase diagram computationally. We will specifically search for phases that are expected to have good performance at high temperatures.<br/><br/>[1] Meng, F., Qiu, J., & Baker, I. (2013). The effects of chromium on the microstructure and tensile behavior of Fe30Mn20Ni34Al15. Materials Science & Engineering A, 586, 45–52. http://dx.doi.org/10.1016/j.msea.2013.08.005