Unveiling the interplay of deformation mechanisms in a metastable high entropy alloy with tuned composition using synchrotron X-ray diffraction

The mechanical behavior of a metastable high entropy alloy (HEA) with composition Fe39-Mn20-Co20-Cr15-Si5-1Al at% is investigated. The deformation mechanisms contributing to its mechanical properties are unveiled, by performing uniaxial tensile tests in situ with synchrotron X-ray diffraction. Three distinct deformation regimes are detected. The initial elastic and early dislocation-based plasticity deformation is followed by a moderate work hardening rate regime, which is associated with the deformation-induced phase formation of epsilon-martensite, with hexagonal close-packed (hcp) crystal structure as well as slip in the parent austenitic phase. During the third deformation regime, the phase transformation continues to occur in combination with 2 modes of hcp twinning as well as slip in the unfavorably oriented grains for twinning. The interplay of all these co-existing deformation mechanisms can be evidenced by synchrotron X-ray diffraction.

Automated summary

The mechanical behavior of a metastable high entropy alloy (HEA) with composition Fe39-Mn20-Co20-Cr15-Si5-1Al at% was investigated, and the deformation mechanisms contributing to its mechanical properties were revealed using in situ uniaxial tensile tests with synchrotron X-ray diffraction. Three distinct deformation regimes were observed, including an initial elastic regime, a dislocation-based plasticity regime, and a phase transformation regime. The phase transformation was accompanied by the formation of hexagonal close-packed (hcp) martensite and slip in the parent austenitic phase, as well as twinning in unfavorably oriented grains.