Microstructure of Plastic Deformation Layer on Grinding Surface of GH4169 Alloy

Abstract

In order to improve the grinding surface integrality of the superalloy GH4169, which usually be used in the aero-engine, the metamorphic layer is investigated by optical microscope, transmission electron microscopy(TEM) and high resolution transmission electron microscopy(HRTEM). The results show that, the severe localized plastic deformation occurred on the grinding surface and subsurface, and a severe plastic deformation layer(SPDL) is formed in the metamorphic layer. Under the experimental conditions, the depth of surface plastic deformation layer is slightly larger than 2.2 μm. According to the microstructure characteristics, SPDL is further divided into three layers: the surface amorphous layer(SAL), the micro-shear band(MSB) and the nanocrystalline layer(NCL). SAL is adjacent to the grinding surface, its microstructure is almost amorphous and contains many vacancies. There are still a certain amount of ordered structures with diameter of 1-3 nm in SAL. MSB is located between SAL and NCL, parallel with the grinding surface and a strip with width of 2 nm. MSB is amorphous completely and has no ordered structure. NCL is close to matrix, mainly consists of nanometer grains with diameter of 10-150 nm. Inside the nanometer grains, there are large amounts of crystal defects, such as amorphizations, dislocations, stacking fault and twins.