The effects of lamellar structure on deformation and fracture behavior in a Ti 48Al 2Mn 2Nb alloy produced by centrifugal spray deposition(CSD) were investigated. The deformation and fracture of samples after tensile ...The effects of lamellar structure on deformation and fracture behavior in a Ti 48Al 2Mn 2Nb alloy produced by centrifugal spray deposition(CSD) were investigated. The deformation and fracture of samples after tensile and compressive tests were examined in a scanning electron microscope (SEM). The in situ tensile testing was further carried out in a SEM and the crack growth path of samples was observed. The result shows that there is a remarkable effect of lamellar structure of CSD TiAl alloy on its deformation and fracture process. Especially, the main crack extension is dependent on the lamellar direction relative to tensile loading axis. SEM observations indicate that there is a shielding toughening effect of lamellar structure on fracture in CSD samples, such as, crack deflection, crack path tortuousity, and crack branching, etc. Moreover, the crack growth path shows that the main crack grows tortuously and uncontinuously by ligaments bridging many microcracks in front of crack tip. The effect mechanism of microstructure on deformation and fracture process is discussed.[展开更多
Magnetron-sputter deposition was used to produce Ti-48Al-8Cr-2Ag coating on a cast alloy substrate with the same composition. Hot corrosion was carried out in molten (Na,K)2SO4 and Na2SO4+NaCl at 900 ℃. The sputtered...Magnetron-sputter deposition was used to produce Ti-48Al-8Cr-2Ag coating on a cast alloy substrate with the same composition. Hot corrosion was carried out in molten (Na,K)2SO4 and Na2SO4+NaCl at 900 ℃. The sputtered nanocrystalline coating shows much better hot-corrosion resistance in molten (Na,K)2SO4 as a result of the formation of a continuous and compact Al2O3 scale. The nanocrystallization of TiAlCrAg alloy prolongs the incubation of breakaway corrosion and improves the hot-corrosion resistance of TiAlCrAg alloy in molten Na2SO4+NaCl. The relevant corrosion mechanism was discussed.展开更多
High-temperature titanium alloy for aeroengine compressor applications suffers from high-temperature oxidation and environmental corrosion, which prohibits long-term service of this kind alloy at temperatures above 60...High-temperature titanium alloy for aeroengine compressor applications suffers from high-temperature oxidation and environmental corrosion, which prohibits long-term service of this kind alloy at temperatures above 600℃. In an attempt to tackle this problem, Ti-48Al （at. pct） and Ti-48Al-12Cr （at. pct） protective coatings were plated on the substrate of alloy Ti-60 by arc ion plating （ALP） method. Isothermal and cyclic oxidation tests were performed in static air at elevated temperatures. Phase composition, morphology of the coatings and distribution of elements were investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and energy dispersive X-ray analysis （EDX）. The results showed that the Ti-48Al coating exhibited good isothermal oxidation resistance during exposure at 800℃, but poorer resistance against oxidation at 900℃. By contrast Ti-48Al-12Cr coating demonstrated excellent isothermal oxidation resistance at both temperatures. Cyclic oxidation tests performed at 800℃ indicated that resistance and no spallation of coatings was observed. But both coatings demonstrated good cyclic oxidation at 900℃ only Ti-48Al-12Cr coating demonstrated excellent cyclic oxidation resistance.展开更多
基金Project (E990 0 0 7)supportedbyFujianProvincialNaturalScienceFoundation P .R .China
文摘The effects of lamellar structure on deformation and fracture behavior in a Ti 48Al 2Mn 2Nb alloy produced by centrifugal spray deposition(CSD) were investigated. The deformation and fracture of samples after tensile and compressive tests were examined in a scanning electron microscope (SEM). The in situ tensile testing was further carried out in a SEM and the crack growth path of samples was observed. The result shows that there is a remarkable effect of lamellar structure of CSD TiAl alloy on its deformation and fracture process. Especially, the main crack extension is dependent on the lamellar direction relative to tensile loading axis. SEM observations indicate that there is a shielding toughening effect of lamellar structure on fracture in CSD samples, such as, crack deflection, crack path tortuousity, and crack branching, etc. Moreover, the crack growth path shows that the main crack grows tortuously and uncontinuously by ligaments bridging many microcracks in front of crack tip. The effect mechanism of microstructure on deformation and fracture process is discussed.[
基金Project(59971052) supported by the National Natural Science Foundation of China
文摘Magnetron-sputter deposition was used to produce Ti-48Al-8Cr-2Ag coating on a cast alloy substrate with the same composition. Hot corrosion was carried out in molten (Na,K)2SO4 and Na2SO4+NaCl at 900 ℃. The sputtered nanocrystalline coating shows much better hot-corrosion resistance in molten (Na,K)2SO4 as a result of the formation of a continuous and compact Al2O3 scale. The nanocrystallization of TiAlCrAg alloy prolongs the incubation of breakaway corrosion and improves the hot-corrosion resistance of TiAlCrAg alloy in molten Na2SO4+NaCl. The relevant corrosion mechanism was discussed.
文摘High-temperature titanium alloy for aeroengine compressor applications suffers from high-temperature oxidation and environmental corrosion, which prohibits long-term service of this kind alloy at temperatures above 600℃. In an attempt to tackle this problem, Ti-48Al （at. pct） and Ti-48Al-12Cr （at. pct） protective coatings were plated on the substrate of alloy Ti-60 by arc ion plating （ALP） method. Isothermal and cyclic oxidation tests were performed in static air at elevated temperatures. Phase composition, morphology of the coatings and distribution of elements were investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and energy dispersive X-ray analysis （EDX）. The results showed that the Ti-48Al coating exhibited good isothermal oxidation resistance during exposure at 800℃, but poorer resistance against oxidation at 900℃. By contrast Ti-48Al-12Cr coating demonstrated excellent isothermal oxidation resistance at both temperatures. Cyclic oxidation tests performed at 800℃ indicated that resistance and no spallation of coatings was observed. But both coatings demonstrated good cyclic oxidation at 900℃ only Ti-48Al-12Cr coating demonstrated excellent cyclic oxidation resistance.
