TC6 titanium alloy samples are processed by laser shock peening （LSP）. Then, some samples are vacu- um annealed at 623 K for 10 h for the study on the thermost.ablity of the nanostructure produced by LSP. The charac...TC6 titanium alloy samples are processed by laser shock peening （LSP）. Then, some samples are vacu- um annealed at 623 K for 10 h for the study on the thermost.ablity of the nanostructure produced by LSP. The characteristics of the strengthened layer and nanostructure are studied by atomic force microscopy（AFM）, scan- ning electron microscope （SEM）, electron backscatter diffraction（EBSD）, X-ray diffraction（XRD）, and transmis- sion electron microscopy（TEM） appliances, meanwhile the enhanced microhardness is tested at cross section. AFM of the processed surface indicates that the deformation is approximately uniform, and LSP slightly increases the roughness. SEM and EBSD of the strengthened cross section show that a phases are compressed to strip- shaped, a proportion of a and ~ phases is shattered to smaller phases from surface to 200 ttm in depth. The sur- face XRD shows that although there is no new produced phase during LSP, the grain size refinement and the in- troduction of lattice micro-strains lead to the broadened peak. The TEM photographs and diffraction patterns in- dicate that the shock wave provides high strain rate deformation and leads to the formation of nanocrystal. Com- pared with the samples before annealing, the dislocation density is lower and the grain-boundary is more distinct in the annealed samples, but the nanocrystal size does not grow bigger after annealing. The microhardness measurement indicates that LSP improves the microhardness of TC6 for about 12.2% on the surface, and the layer affected by LSP is about 500/~m in depth. The microhardness after annealing is 10 HVo.5 lower, but the affected depth does not change. The thermostable study shows that the strengthened layer of TC6 processed by LSP is stable at 623 K. The strengthened thermostable layer can significantly improve the fatigue resistance, wear resis- tance and stress corrosion resistance of the titanium alloy. The study results break the USA standard AMS2546 that titanium parts after LSP are subjected in subsequent processing within 589 K.展开更多
A NiCrAlY coating was deposited on the TC6 titanium substrate by arc ion plating （ALP）. The structure and morphologies of the NiCrAlY coating were characterized by X-ray diffraction （XRD） and scanning electron mic...A NiCrAlY coating was deposited on the TC6 titanium substrate by arc ion plating （ALP）. The structure and morphologies of the NiCrAlY coating were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）, and the influence of vacuum heat treatment on the element diffusion behavior was studied. The results showed that the y＇-Ni3Al phase was precipitated on the NiCrAlY coating after heat treatment. The Ni3（AI,Ti）, TiNi, and Ti2Ni intermetallic layers appeared at the interface from the outside to the inside at 700℃, and the thickness of the intermetallic layers increased with the increase in temperature. At 700℃ Ti and Ni were the major diffusion elements, and the diffusion of Cr was observed when the heat treatment temperature increased up to 870℃. The violent inward diffusion of Ni at 950℃ resulted in the degradation of the NiCrAlY coating.展开更多
文摘TC6 titanium alloy samples are processed by laser shock peening （LSP）. Then, some samples are vacu- um annealed at 623 K for 10 h for the study on the thermost.ablity of the nanostructure produced by LSP. The characteristics of the strengthened layer and nanostructure are studied by atomic force microscopy（AFM）, scan- ning electron microscope （SEM）, electron backscatter diffraction（EBSD）, X-ray diffraction（XRD）, and transmis- sion electron microscopy（TEM） appliances, meanwhile the enhanced microhardness is tested at cross section. AFM of the processed surface indicates that the deformation is approximately uniform, and LSP slightly increases the roughness. SEM and EBSD of the strengthened cross section show that a phases are compressed to strip- shaped, a proportion of a and ~ phases is shattered to smaller phases from surface to 200 ttm in depth. The sur- face XRD shows that although there is no new produced phase during LSP, the grain size refinement and the in- troduction of lattice micro-strains lead to the broadened peak. The TEM photographs and diffraction patterns in- dicate that the shock wave provides high strain rate deformation and leads to the formation of nanocrystal. Com- pared with the samples before annealing, the dislocation density is lower and the grain-boundary is more distinct in the annealed samples, but the nanocrystal size does not grow bigger after annealing. The microhardness measurement indicates that LSP improves the microhardness of TC6 for about 12.2% on the surface, and the layer affected by LSP is about 500/~m in depth. The microhardness after annealing is 10 HVo.5 lower, but the affected depth does not change. The thermostable study shows that the strengthened layer of TC6 processed by LSP is stable at 623 K. The strengthened thermostable layer can significantly improve the fatigue resistance, wear resis- tance and stress corrosion resistance of the titanium alloy. The study results break the USA standard AMS2546 that titanium parts after LSP are subjected in subsequent processing within 589 K.
基金This study was supported by the National Key Program of the Tenth Five-Year Plan of China (05-MKP-089).
文摘A NiCrAlY coating was deposited on the TC6 titanium substrate by arc ion plating （ALP）. The structure and morphologies of the NiCrAlY coating were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）, and the influence of vacuum heat treatment on the element diffusion behavior was studied. The results showed that the y＇-Ni3Al phase was precipitated on the NiCrAlY coating after heat treatment. The Ni3（AI,Ti）, TiNi, and Ti2Ni intermetallic layers appeared at the interface from the outside to the inside at 700℃, and the thickness of the intermetallic layers increased with the increase in temperature. At 700℃ Ti and Ni were the major diffusion elements, and the diffusion of Cr was observed when the heat treatment temperature increased up to 870℃. The violent inward diffusion of Ni at 950℃ resulted in the degradation of the NiCrAlY coating.
