Microstructures of nanocrystalline surface layer of 7050 aluminum alloy
SONG Ying-gang;WANG Xin;WANG Qiang;Beijing Institute of Aeronautical Materials;
A nanostructured surface layer was fabricated on 7050 aluminum alloy by using shot peening technique. The structure and properties of the nanostructure surface layer were characterized by means of Electron back-scattering diffraction( EBSD),transmission electron microscope( TEM) and X-ray diffraction. The results show that a nanostructured surface layer with the depth of about 150 μm is formed after shot peening. The layer is composed of nanometer structures varying in orientation coming from the original grain refinement. The residual stress on surface turns into tensile and the hardness decreases significantly. Compare to the bulk material,the surface hardness decreases by about 70%.