Nonuniformity of morphology and mechanical properties on the surface of single crystal superalloy subjected to laser shock peening

Surface topography and microhardness of a Ni-based single crystal superalloy subjected to laser shock peening (LSP) were investigated. So many morphological surface reliefs were found on the shocked surface, and a microscopic formation mechanism of those surface reliefs was proposed. The formation of surface reliefs can be attributed to the plastic deformation of gamma' precipitates and gamma matrix channels in the lateral or longitudinal directions. The nonuniformity of structures of the deformed surface layer was ascribed to the formation of surface reliefs. The microhardness of surface reliefs was higher than that of adjacent matrixes, so a nonuniformity of micromechanical properties coexisted on the surface of sample subjected to LSP. With the increase of LSP impact times, micromechanical properties difference between surface reliefs and adjacent matrixes widened due to a very high proportion of the longitudinal deformation of gamma' phases contained in the surface relief structures. (C) 2015 Elsevier B.V. All rights reserved.