Grain visualization of FeCoCrMnNi and AlCoCrFeNi_2.1 high-entropy alloys by nanosecond pulse laser irradiation

Characterizing grains is the most common method in materials science research, but the existing techniques for grain characterization are generally expensive and time-consuming. In this study, nanosecond pulse laser irradiation with low laser fluence is attempted to visualize the grains of two typical high-entropy alloys (HEAs) with different crystal structures and elemental compositions. The effects of laser parameters and gas atmospheres on the laser visualization of grains are comparatively investigated. Under specific laser irradiation conditions, the grains of these two HEAs could be well visualized by producing different surface nanostructures. By experiments and analysis, the underlying mechanisms of laser visualization of grains under different conditions are elucidated, and the role of O element on the promotion of the visualization of grain boundaries is confirmed. This study provides a simple and efficient method to visualize the grains of HEAs, and on the other hand, enhances the understanding of nanosecond laser-HEA interaction.