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 展开更多
Effect of annealing and solution treatment prior to cryorolling on the formation of initial structure influencing microstructure formation from nano to micron scale and resultant mechanical and corrosion properties in...Effect of annealing and solution treatment prior to cryorolling on the formation of initial structure influencing microstructure formation from nano to micron scale and resultant mechanical and corrosion properties in Al 1100 alloy has been studied in detail.Before subjecting to 50%cryorolling,samples were pre-annealed at 250℃ for 2 h and pre-solution treated at 540℃ for 1 h.X-ray diffraction and HRTEM techniques were used to understand the crystallite size,lattice strain and dislocation configuration in the processed alloy.The results indicate that the pre-annealed sample has the highest grain aspect ratio(4.43),the smallest crystallite size(37.53 nm),the highest lattice strain(9.12×10^(−3))and the highest dislocation density(45.16×10^(13) m^(−2))among the tested sample.The pre-annealed sample shows a significant improvement of 43.44%,24.64%and 20.33%in hardness,ultimate tensile strength and yield strength.Both pre-annealed and pre-solution treated samples show improved corrosion resistance when compared to cryorolled samples without any pre-treatment,with the pre-annealed sample showing the best corrosion resistance.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
基金Universiti Sains Malaysia for providing the fund for this study under RU grant No.1001/PBahan/8014105.
文摘Effect of annealing and solution treatment prior to cryorolling on the formation of initial structure influencing microstructure formation from nano to micron scale and resultant mechanical and corrosion properties in Al 1100 alloy has been studied in detail.Before subjecting to 50%cryorolling,samples were pre-annealed at 250℃ for 2 h and pre-solution treated at 540℃ for 1 h.X-ray diffraction and HRTEM techniques were used to understand the crystallite size,lattice strain and dislocation configuration in the processed alloy.The results indicate that the pre-annealed sample has the highest grain aspect ratio(4.43),the smallest crystallite size(37.53 nm),the highest lattice strain(9.12×10^(−3))and the highest dislocation density(45.16×10^(13) m^(−2))among the tested sample.The pre-annealed sample shows a significant improvement of 43.44%,24.64%and 20.33%in hardness,ultimate tensile strength and yield strength.Both pre-annealed and pre-solution treated samples show improved corrosion resistance when compared to cryorolled samples without any pre-treatment,with the pre-annealed sample showing the best corrosion resistance.
