Hydrogen-induced cracking (HIC) of two-phase alloy of Ni3AI+NiAI was in situ investigated using a WOL (wedge opening-loading) constant deflection specimen in an optical microscopy and using a notched tensile specimen ...Hydrogen-induced cracking (HIC) of two-phase alloy of Ni3AI+NiAI was in situ investigated using a WOL (wedge opening-loading) constant deflection specimen in an optical microscopy and using a notched tensile specimen in scanning electron microscopy (SEM). Results showed that the threshold stress intensity of HIC was KIH=15.7 MPa·m1/2, and (da/dt)II=0.019 mm/h. For the uncharged specimen, microcrack initiated and propagated preferentially within the NiAl phase, resulting in cleavage fracture, but for the precharged specimen with hydrogen concentration of 24.7×10-4%, hydrogen-induced crack initiated and propagated preferentially along the Ni3AI/NiAI interfaces, resulting in interphase fracture.展开更多
Ni-Al system intermetallic compound coatings were acquired on the substrates of Nickel base superalloy by thermal spray accompanied with metallurgy and diffusion process. The main phases in the coatings are NiAl and N...Ni-Al system intermetallic compound coatings were acquired on the substrates of Nickel base superalloy by thermal spray accompanied with metallurgy and diffusion process. The main phases in the coatings are NiAl and Ni3Al and the microstructure oi" the coatings are dense. The coatings bond well with the substrates and show excellent characteristics of oxidation-resistance at temperature as high as 1300 °C. The coatings have been applied successfully in industry.展开更多
基金This project was supported by the special fund for the Major State Basic Research Projects(G19990650)the NSFC(No.59895150).
文摘Hydrogen-induced cracking (HIC) of two-phase alloy of Ni3AI+NiAI was in situ investigated using a WOL (wedge opening-loading) constant deflection specimen in an optical microscopy and using a notched tensile specimen in scanning electron microscopy (SEM). Results showed that the threshold stress intensity of HIC was KIH=15.7 MPa·m1/2, and (da/dt)II=0.019 mm/h. For the uncharged specimen, microcrack initiated and propagated preferentially within the NiAl phase, resulting in cleavage fracture, but for the precharged specimen with hydrogen concentration of 24.7×10-4%, hydrogen-induced crack initiated and propagated preferentially along the Ni3AI/NiAI interfaces, resulting in interphase fracture.
文摘Ni-Al system intermetallic compound coatings were acquired on the substrates of Nickel base superalloy by thermal spray accompanied with metallurgy and diffusion process. The main phases in the coatings are NiAl and Ni3Al and the microstructure oi" the coatings are dense. The coatings bond well with the substrates and show excellent characteristics of oxidation-resistance at temperature as high as 1300 °C. The coatings have been applied successfully in industry.
