Effect of Various Processes on Microstructure of CoCrFeNiAlx High-Entropy Alloy Shot Peening Layer

Abstract

The change in microstructure caused by shot peening can strengthen the material and play an important role in improving the fatigue properties of the material. In order to investigate the related properties such as plastic strain anddislocation activity, the microstructure of CoCrFeNiAlx alloy shot peening layer under different processes was studied. The material exhibited a single austenitic phase, and the FCC crystal structure remained unchanged despite variations in shot peening intensity. Microstructure analysis indicates that with the increase in shot peening intensity, the grain size of the shot peening layer decreases obviously, and the content of microscopic distortion on the surface of the shot peening layer is the highest, and gradually decreases with the increase in depth. At the same time, the roughness of the sample surface is also reduced, which can enhance the fatigue strength and life of the sample. A TEM study revealed the microstructure of the shot peening layer. During the impact of shot peening, the twins produced gradually subdivided the initial grain into smaller slices. With the accumulation of plastic strain, dislocation activity begins to dominate the deformation process. The deformation-induced dislocations accumulate gradually in the small pieces and accumulate into dislocations perpendicular to the secondary twins. These results could be conducive to providing reference and theoretical basis for improving and strengthening the mechanical properties of a series of materials such as high-entropy alloy.