Distributions of Grain Boundary Population and Energy in High-Entropy Alloy

In the past decade, high-entropy alloys (HEAs) formed by mixing of five or more elements; i.e. FeMnNiCoCr, AlCoCrCuFeNi, AlCrFeMnNi and etc, have gained extensive interests due to their exceptional mechanical strength and excellent corrosion, wear and irradiation resistances.  As a result of their high configurational entropies, the reduction of Gibbs Free energies and the strong lattice distortions originated from the multiple alloy elements provide a novel strategy to fabricate the alloys that can withstand extreme conditions (high pressure, temperature, and irradiation).  While the design criterions for the stable face-centered cubic (fcc) structured single phase solid solution HEAs have been thoroughly investigated, the relative grain boundary population distribution, known as a grain boundary character distribution (GBCD), was rarely examined and documented.  Because the reliability and performance of the HEA polycrystallines are strongly influenced by the GBCDs, it is necessary to investigate the GBCDs in the single phase solid solution HEAs.  Recently, the principal investigator (PI, MRG6080253) reported that there is a strong inverse correlation between the grain boundary population and the simulated grain boundary energy in the austenitic high-manganese steel.  Because of its high fraction of manganese (~20%) in the austenitic steel, the grain boundary populations and energies in the austenitic steel and HEAs might be equivalent.  The objective of this proposal is therefore to investigate the relationship between the GBCD in FeMnNiCoCr and the grain boundary energy distribution (GBED) simulated by using atomistic computer simulations.  If the relationship between grain boundary population and energy in the FeMnNiCoCr exhibits the same trends as in the austenitic steel and pure metals with the same fcc structure, the multiple alloy elements could have minor effects on the grain boundary structures and energies.  It is expected that this study would promote the development of high-entropy alloys for aircraft, automotive parts and the first nuclear fusion reactor in Thailand, Center for Plasma and Nuclear Fusion Technology (CPaF), Thailand Institute of Nuclear Technology.