TaN/NbN multilayered coatings with nanoscale bilayer periods were synthesized at different Ar/N2 flow rates by RF （radio frequency） magnetron sputtering. XRD （X-ray diffraction） and Nano Indenter System were emplo...TaN/NbN multilayered coatings with nanoscale bilayer periods were synthesized at different Ar/N2 flow rates by RF （radio frequency） magnetron sputtering. XRD （X-ray diffraction） and Nano Indenter System were employed to investigate the influence of Ar/N2 flow rate （FAr：FN2） on microstructure and mechanical properties of the coatings. The low-angle XRD pattern indicated a well-defined composition modulation and layer structure of the multilayered coating. All multilayered coatings almost revealed higher hardness than the rule-of-mixtures value of monolithic TaN and NbN coatings. At FAr：FN2=10, the multilayered coating possessed desirable hardness, elastic modulus, internal stress, and fracture resistance, compared with ones synthesized at other Ar/N2 flow rates. The layered structure with strong mixture of TaN （110）, （111）, （200） and Nb2N （101）textures should be related to the enhanced mechanical properties.展开更多
A high performance Ni-Al-Mo-B system cast Ni_3Al base alloy, named Alloy IC6, has been developed for advanced gas turbine blades and vanes. The alloy has high strength and ductility from room temperature to 1100℃ as...A high performance Ni-Al-Mo-B system cast Ni_3Al base alloy, named Alloy IC6, has been developed for advanced gas turbine blades and vanes. The alloy has high strength and ductility from room temperature to 1100℃ as well as excellent creep resistance over a wide temperature range of 760℃ to 1100℃ . The superior mechanical properties of this alloy.may be attributed to (1) solid solution hardening by the large amount of Mo addition , (2)second phase strengthening by γ-phase and other minor phases that precipitate in various temperature ranges, (3) rearrangement of γ-phase in the form of raft structure during creep deformation , (4) high-density misfit dislocation networks at the γ /γ' interfaces that form due to a high value ofγ /γ ' misfit .展开更多
Rare metals play an important role in development of superalloys. Over the last two decades, the application of the rare metals in superalloys has achieved progress significantly. They present multi-beneficial effects...Rare metals play an important role in development of superalloys. Over the last two decades, the application of the rare metals in superalloys has achieved progress significantly. They present multi-beneficial effects for strengthening the matrix and the cophase, increasing the lattice misfit, cleaning the grain boundary, improving the carbides and eutectics, refining the grain, stabilizing the oxidation film, etc., so that the elevated temperature rupture life and elevated temperature oxidation resistance are improved significantly, leading to a broad application in the superalloys. In order to meet the higher demand for better superalloys in the future, more intensive research is necessary on the effects of the rare metals on the superalloy, and especially on the combination effect of various rare metals and mutual influence among them. Utilization of the computational materials science and combinatorial high throughput experiment will be of importance in application of rare metals in superalloys.展开更多
文摘TaN/NbN multilayered coatings with nanoscale bilayer periods were synthesized at different Ar/N2 flow rates by RF （radio frequency） magnetron sputtering. XRD （X-ray diffraction） and Nano Indenter System were employed to investigate the influence of Ar/N2 flow rate （FAr：FN2） on microstructure and mechanical properties of the coatings. The low-angle XRD pattern indicated a well-defined composition modulation and layer structure of the multilayered coating. All multilayered coatings almost revealed higher hardness than the rule-of-mixtures value of monolithic TaN and NbN coatings. At FAr：FN2=10, the multilayered coating possessed desirable hardness, elastic modulus, internal stress, and fracture resistance, compared with ones synthesized at other Ar/N2 flow rates. The layered structure with strong mixture of TaN （110）, （111）, （200） and Nb2N （101）textures should be related to the enhanced mechanical properties.
文摘A high performance Ni-Al-Mo-B system cast Ni_3Al base alloy, named Alloy IC6, has been developed for advanced gas turbine blades and vanes. The alloy has high strength and ductility from room temperature to 1100℃ as well as excellent creep resistance over a wide temperature range of 760℃ to 1100℃ . The superior mechanical properties of this alloy.may be attributed to (1) solid solution hardening by the large amount of Mo addition , (2)second phase strengthening by γ-phase and other minor phases that precipitate in various temperature ranges, (3) rearrangement of γ-phase in the form of raft structure during creep deformation , (4) high-density misfit dislocation networks at the γ /γ' interfaces that form due to a high value ofγ /γ ' misfit .
基金The supports from State Basic Research Development Program of China(No.2010BC100404)Shanghai Science and Technology Committee
文摘Rare metals play an important role in development of superalloys. Over the last two decades, the application of the rare metals in superalloys has achieved progress significantly. They present multi-beneficial effects for strengthening the matrix and the cophase, increasing the lattice misfit, cleaning the grain boundary, improving the carbides and eutectics, refining the grain, stabilizing the oxidation film, etc., so that the elevated temperature rupture life and elevated temperature oxidation resistance are improved significantly, leading to a broad application in the superalloys. In order to meet the higher demand for better superalloys in the future, more intensive research is necessary on the effects of the rare metals on the superalloy, and especially on the combination effect of various rare metals and mutual influence among them. Utilization of the computational materials science and combinatorial high throughput experiment will be of importance in application of rare metals in superalloys.
