Abstract: The rapidly increasing scientific interest in 3D-printed high-entropy alloys (HEAs) necessitates the understanding of their deformation mechanisms. Here, we present the grain rotation behavior of a nearly equiatomic CrMnFeCoNi HEA fabricated with laser-beam powder bed fusion via quasi in-situ electron backscatter diffraction (EBSD) observations during compressive deformation. The rotation paths of grains can be predicted via a new lattice reorientation factor (𝑚_𝐴), defined as the average of primary and secondary slip Schmid factors. The grains that initially have their 〈111〉 directions oriented close to the loading direction with low-to-intermediate 𝑚_𝐴 values tend to rotate towards the 〈101〉 pole. The grains initially oriented in the center of inverse pole figures with high 𝑚_𝐴 values develop multiple rotation paths pointing away from the 〈001〉 pole. The cube-oriented grains with their 〈001〉 directions close to the loading direction undergo face-centered cubic (FCC)-to-hexagonal close-packed (HCP) phase transformation due to the activation of octahedral slip involving multiple slip systems. This transformation can be well elucidated via a modified parameter, defined as the average of four maximum Schmid factors on each of four {111} slip/twinning planes in FCC crystals. The findings provide new insights into the underlying mechanisms for deformation-induced grain rotation and phase transformation, and help pave the way for developing advanced HEAs via transformation-induced plasticity.

Key words: Electron backscatter diffraction, High-entropy alloy, Grain rotation, Phase transformation, Schmid factor, Quasi in-situ observations