Surface Modification of TC17 Alloy by Shot-Peening and with Micro-Arc Oxidized Coating

The surfaces of TC17 Ti-alloy,an advanced aircraft engine blade material,were modified first by shot-peening and then by micro-arc oxidation(MAO).The microstructures and tribological behavior of the surface modified TC17 Ti-alloy were characterized with X-ray diffraction,scanning electron microscopy and conventional mechanical tools.The preliminary results show that the shot-peening significantly affected the compactness/thickness/density/porosity/hardness/corrosion-resistance/residual-stress of the MAO coatings because of the considerable reduction of grain-size,decrease of micro-voids and surface reconstruction.Specifically,the shot-peening greatly enhanced the hardness of TC17 alloy up to 463 HV0.1,with a top-down decreasing depth hardness profile,and increased the fatigue-life by 15% to 15,361 weeks.The growth of quite a few fatigue-sources into the substrate,induced by the shot peening,were observed.As expected,the MAO coating increased the corrosion resistance because MAO layer sealed the micro-pores of the alloy.