β-NiAl is a potential oxidation-resistant coating material to be operated at temperatures above 1 150 ℃. In this paper,β-NiAl coatings with 0-0.5 at% Dy are prepared by electron beam physical vapor deposition (EB-...β-NiAl is a potential oxidation-resistant coating material to be operated at temperatures above 1 150 ℃. In this paper,β-NiAl coatings with 0-0.5 at% Dy are prepared by electron beam physical vapor deposition (EB-PVD). Transient oxidation behavior of the coatings is investigated. At 1 200 ℃, only stable α-Al2O3 phase is observed on the 0.05 at% doped coating, whereas the phase transfomlation from θ-Al2O3 to α-Al2O3 occurs in the 0.5 at% Dy doped coating during 1 h oxidation. At 1 100 ℃, all the coatings reveal the transient transformation of θ-α in the early 15 min and the transformation for the 0.05 at% Dy doped coating is completed within 45 min, much earlier than that for the 0.5 at% Dy doped coating. Overdoping of Dy retards the transformation of θ-α. The undoped and overdoped coatings reveal the whisker structure of θ-Al2O3 even after 20 h oxidation at 1 100 ℃, while the 0.05 at% Dy coating reveals typical granulated structure of α-Al2O3.展开更多
Thermal barrier coatings(TBCs) consisting ofLa_(2)Ce_(2)O_(7)(LCO) and Y_(2)O_(3)-stabilized-ZrO_(2)(YSZ) doubleceramic layer and Dy/Pt co-doped NiAl bond coat were produced by electron beam physical vapor deposition(...Thermal barrier coatings(TBCs) consisting ofLa_(2)Ce_(2)O_(7)(LCO) and Y_(2)O_(3)-stabilized-ZrO_(2)(YSZ) doubleceramic layer and Dy/Pt co-doped NiAl bond coat were produced by electron beam physical vapor deposition(EBPVD). Thermal cyclic performance of the TBCs was evaluated by flame shock testing at 1300 ℃. For comparison, the TBCs with a undoped NiAl bond coat were also studied. The microstructural evolution and failure mechanisms of the above TBCs during thermal cycling were investigated. Spallation failure of the TBCs with the undoped bond coat occurs after around 500 cycles by cracking at the interface between YSZ ceramic layer and thermally grown oxides(TGO) layer. The TBCs with Pt/Dy modified bond coat reveal improved interface bonding even after 1200 thermal cycles, whereas some delamination cracks are presented in the LCO layer. On the other hand,the Pt/Dy modified bond coat effectively suppresses the formation of the needle-like topologically closed packed phases(TCP) in the single crystal superalloy.展开更多
The effects of YO(1.5)doping in yttria-zirconia based thermal barrier coatings(TBCs)against CMAS interaction/infiltration are discussed.The TBCs with an YO(1.5)content ranging from 43–67 mol.%(balance Zr O2)were prod...The effects of YO(1.5)doping in yttria-zirconia based thermal barrier coatings(TBCs)against CMAS interaction/infiltration are discussed.The TBCs with an YO(1.5)content ranging from 43–67 mol.%(balance Zr O2)were produced by electron beam physical vapor deposition(EB-PVD)techniques.The results reveal a trend of higher apatite formation probability with the higher free YO(1.5)available in the yttriazirconia system.Additionally,the infiltration resistance and amount of consumed coating appears to be strongly dependent on the YO(1.5)content in the coating.The thinnest reaction layer and lowest infiltration was found for the highest produced 67 YO(1.5)coating.Complementary XRD experiments with volcanic ash/YO(1.5)powder mixtures with higher yttria contents than in the coatings(80 YO(1.5)and pure YO(1.5))also showed higher apatite formation with respect to increasing yttria content.The threshold composition to promote apatite-based reaction products was found to be around 50 YO(1.5)in zirconia which was proved in the coatings and XRD powder experiments.An YO(1.5)-ZrO2-Fe O-TiO2 bearing zirconolite-type phase was formed as a reaction product for all the coating compositions which implicates that TiO2 in the melt acts as a trigger for zirconolite formation.This phase could be detrimental for CMAS/volcanic ash infiltration resistance since it can be formed alongside with apatite which controls or limits the amount of Y^(3+)available for glass crystallization.The Fe rich garnet phase containing all the possible elements exhibited a slower nucleation compared to apatite and its growth was enhanced with slow cooling rates.The implications of phase stability and heat treatment effects on the reaction products are discussed for tests performed at 1250°C.展开更多
In this research, a nano-Mo2 C particle dispersion-strengthened copper alloy was prepared by a novel method, i.e., electron beam physical vapor deposition(EBPVD) which has advantages of simple technical process and ...In this research, a nano-Mo2 C particle dispersion-strengthened copper alloy was prepared by a novel method, i.e., electron beam physical vapor deposition(EBPVD) which has advantages of simple technical process and low cost compared with the conventional mechanical alloying method. And the microstructure and properties of the material were investigated. The results show that the copper matrix is composed of columnar crystals with the average width of 7 lm, and the size of Mo2 C dispersoid is1–7 nm. The ultimate tensile strength of the material is486 MPa, and the electrical conductivity is 82 % IACS. As the temperature increases from 293 to 573 K, the material becomes more brittle.展开更多
The process of electron beam vacuum deposition of the Fe-(35-38 wt%)Ni alloys at substrate temperatures Ts from 300 to700 ℃ were used to produce vacuum-deposited foils with the FCC structure, differing by the size ...The process of electron beam vacuum deposition of the Fe-(35-38 wt%)Ni alloys at substrate temperatures Ts from 300 to700 ℃ were used to produce vacuum-deposited foils with the FCC structure, differing by the size of characteristic microstructural elements (grains and subgrains). It was shown that refinement of foil microstructural elements to nanoscale is accompanied by their microhardness increase up to 4-5 GPa. The change of the thermal expansion coefficient (TEC) of the nanostructured (NS) foil of the Fe-35.1Ni alloy within the temperature range from -50 to 150 ℃ has some deviation from that observed for cast Invar alloy of the same composition. It has been found that the main factors affecting the peculiarities of thermal expansion of the NS foil can be related to the presence of small fraction of BCC- phase in them, high level of crystalline lattice microstrains and inhomogeneous magnetic order in FCC- phase. It was shown that as a result of additional thermal treatment of NS foils their invar properties become similar to that observed for cast Invar alloy but mechanical properties remain on the same level.展开更多
The Cr-/Si-modified Ni Al Hf coatings were produced on single-crystal(SC) superalloy N5 by electron beam physical vapor deposition(EB-PVD). The cyclic oxidation behavior of the coatings at 1100 °C was investi...The Cr-/Si-modified Ni Al Hf coatings were produced on single-crystal(SC) superalloy N5 by electron beam physical vapor deposition(EB-PVD). The cyclic oxidation behavior of the coatings at 1100 °C was investigated. The microstructures of the oxide scales grown on the coatings were characterized by scanning electron microscope(SEM) with energy-dispersive X-ray spectrum(EDX),electron probe micro-analyzer(EPMA) and X-ray diffraction(XRD). The effects of Cr and Si on the cyclic oxidation behavior of the Ni Al Hf coatings were discussed. The addition of Si to the Ni Al Hf Cr coating not only reduces the oxidation rate but also enhances the oxide scale adherence.Owing to the addition of Si in the coating, the segregation of Cr and Mo beneath the oxide scale is effectively avoided,which contributes to enhancing oxide scale adherence.展开更多
基金National Natural Science Foundation of China (50771009, 50731001) National Basic Research Program of China (2010CB631200) Research Fund for the Doctoral Program of Higher Education of China (20070006017)
文摘β-NiAl is a potential oxidation-resistant coating material to be operated at temperatures above 1 150 ℃. In this paper,β-NiAl coatings with 0-0.5 at% Dy are prepared by electron beam physical vapor deposition (EB-PVD). Transient oxidation behavior of the coatings is investigated. At 1 200 ℃, only stable α-Al2O3 phase is observed on the 0.05 at% doped coating, whereas the phase transfomlation from θ-Al2O3 to α-Al2O3 occurs in the 0.5 at% Dy doped coating during 1 h oxidation. At 1 100 ℃, all the coatings reveal the transient transformation of θ-α in the early 15 min and the transformation for the 0.05 at% Dy doped coating is completed within 45 min, much earlier than that for the 0.5 at% Dy doped coating. Overdoping of Dy retards the transformation of θ-α. The undoped and overdoped coatings reveal the whisker structure of θ-Al2O3 even after 20 h oxidation at 1 100 ℃, while the 0.05 at% Dy coating reveals typical granulated structure of α-Al2O3.
基金financially sponsored by the National Natural Science Foundations of China(Nos.51590894,51425102 and 51231001)。
文摘Thermal barrier coatings(TBCs) consisting ofLa_(2)Ce_(2)O_(7)(LCO) and Y_(2)O_(3)-stabilized-ZrO_(2)(YSZ) doubleceramic layer and Dy/Pt co-doped NiAl bond coat were produced by electron beam physical vapor deposition(EBPVD). Thermal cyclic performance of the TBCs was evaluated by flame shock testing at 1300 ℃. For comparison, the TBCs with a undoped NiAl bond coat were also studied. The microstructural evolution and failure mechanisms of the above TBCs during thermal cycling were investigated. Spallation failure of the TBCs with the undoped bond coat occurs after around 500 cycles by cracking at the interface between YSZ ceramic layer and thermally grown oxides(TGO) layer. The TBCs with Pt/Dy modified bond coat reveal improved interface bonding even after 1200 thermal cycles, whereas some delamination cracks are presented in the LCO layer. On the other hand,the Pt/Dy modified bond coat effectively suppresses the formation of the needle-like topologically closed packed phases(TCP) in the single crystal superalloy.
基金The Deutsche Forschungsgemeinschaft(DFG)under grant No.Schu1372/5-1,Consejo Nacional de Ciencia y Tecnologia(CONACYT)National Science Foundation(NSF)with NSF-PREM grant No.DMR-1827745。
文摘The effects of YO(1.5)doping in yttria-zirconia based thermal barrier coatings(TBCs)against CMAS interaction/infiltration are discussed.The TBCs with an YO(1.5)content ranging from 43–67 mol.%(balance Zr O2)were produced by electron beam physical vapor deposition(EB-PVD)techniques.The results reveal a trend of higher apatite formation probability with the higher free YO(1.5)available in the yttriazirconia system.Additionally,the infiltration resistance and amount of consumed coating appears to be strongly dependent on the YO(1.5)content in the coating.The thinnest reaction layer and lowest infiltration was found for the highest produced 67 YO(1.5)coating.Complementary XRD experiments with volcanic ash/YO(1.5)powder mixtures with higher yttria contents than in the coatings(80 YO(1.5)and pure YO(1.5))also showed higher apatite formation with respect to increasing yttria content.The threshold composition to promote apatite-based reaction products was found to be around 50 YO(1.5)in zirconia which was proved in the coatings and XRD powder experiments.An YO(1.5)-ZrO2-Fe O-TiO2 bearing zirconolite-type phase was formed as a reaction product for all the coating compositions which implicates that TiO2 in the melt acts as a trigger for zirconolite formation.This phase could be detrimental for CMAS/volcanic ash infiltration resistance since it can be formed alongside with apatite which controls or limits the amount of Y^(3+)available for glass crystallization.The Fe rich garnet phase containing all the possible elements exhibited a slower nucleation compared to apatite and its growth was enhanced with slow cooling rates.The implications of phase stability and heat treatment effects on the reaction products are discussed for tests performed at 1250°C.
基金financially supported by the National Natural Science Foundation of China (Nos. 51104131 and 51201152)Heilongjiang Provincial Natural Science Foundation of China (No. E201247)the Open Fund of Zhejiang Provincial Top Key Discipline (No. 20110929)
文摘In this research, a nano-Mo2 C particle dispersion-strengthened copper alloy was prepared by a novel method, i.e., electron beam physical vapor deposition(EBPVD) which has advantages of simple technical process and low cost compared with the conventional mechanical alloying method. And the microstructure and properties of the material were investigated. The results show that the copper matrix is composed of columnar crystals with the average width of 7 lm, and the size of Mo2 C dispersoid is1–7 nm. The ultimate tensile strength of the material is486 MPa, and the electrical conductivity is 82 % IACS. As the temperature increases from 293 to 573 K, the material becomes more brittle.
基金the financing support of the budget(022/11-B)of the G.V.Kurdyumov Institute for Metal Physics of NAS of Ukrainethe budget(1.6.3.13/33) of the E.O.Paton Electric Welding Institute of NAS of Ukraine
文摘The process of electron beam vacuum deposition of the Fe-(35-38 wt%)Ni alloys at substrate temperatures Ts from 300 to700 ℃ were used to produce vacuum-deposited foils with the FCC structure, differing by the size of characteristic microstructural elements (grains and subgrains). It was shown that refinement of foil microstructural elements to nanoscale is accompanied by their microhardness increase up to 4-5 GPa. The change of the thermal expansion coefficient (TEC) of the nanostructured (NS) foil of the Fe-35.1Ni alloy within the temperature range from -50 to 150 ℃ has some deviation from that observed for cast Invar alloy of the same composition. It has been found that the main factors affecting the peculiarities of thermal expansion of the NS foil can be related to the presence of small fraction of BCC- phase in them, high level of crystalline lattice microstrains and inhomogeneous magnetic order in FCC- phase. It was shown that as a result of additional thermal treatment of NS foils their invar properties become similar to that observed for cast Invar alloy but mechanical properties remain on the same level.
基金financially supported by the National Basic Research Program of China (Nos. 2012CB625100 and 2010CB631200)the National Natural Science Foundation of China (No. 51231001)
文摘The Cr-/Si-modified Ni Al Hf coatings were produced on single-crystal(SC) superalloy N5 by electron beam physical vapor deposition(EB-PVD). The cyclic oxidation behavior of the coatings at 1100 °C was investigated. The microstructures of the oxide scales grown on the coatings were characterized by scanning electron microscope(SEM) with energy-dispersive X-ray spectrum(EDX),electron probe micro-analyzer(EPMA) and X-ray diffraction(XRD). The effects of Cr and Si on the cyclic oxidation behavior of the Ni Al Hf coatings were discussed. The addition of Si to the Ni Al Hf Cr coating not only reduces the oxidation rate but also enhances the oxide scale adherence.Owing to the addition of Si in the coating, the segregation of Cr and Mo beneath the oxide scale is effectively avoided,which contributes to enhancing oxide scale adherence.