Dislocation network with pair-coupling structure in {111} γ/γ′ interface of Ni-based single crystal superalloy
نویسندگان
چکیده
The γ/γ' interface dislocation network is reported to improve the high temperature creep resistance of single crystal superalloys and is usually found to deposit in {001} interface. In this work, a new type of dislocation network was found in {111} γ/γ' interface at a single crystal model superalloy crept at 1100 °C/100 MPa. The dislocations in the network are screw with Burgers vectors of 1/2 a<110> and most interestingly, they exhibit a pair-coupling structure. Further investigation indicates that the formation of {111} interface dislocation network occurs when the γ' raft structure begins to degrade by the dislocations cutting into the rafted γ' through the interface. In this condition, the pair-coupling structure is established by the dislocations gliding in a single {111} plane of γ', in order to remove the anti-phase boundary in γ'; these dislocations also act as diffusion channels for dissolving of the γ' particle that is unstable under the interfacial stress from lattice misfit, which leads to the formation of {111}-type zigzag interface. The formation of this network arises as a consequence of more negative misfit, low-alloying γ' particle and proper test conditions of temperature and stress.
منابع مشابه
Evaluating the Effect of Ta/W Ratio on Microstructure and Stress Rupture Properties of Ni-Based Single Crystal Superalloy PWA1483
In this study, the effect of Ta/W ratio on the microstructure and stress rupture properties of Ni-based single crystal (SX) superalloy PWA1483 was investigated. For this purpose, single crystal (SX) superalloys with different Ta/W ratios (0.75, 1.0, 1.32 and 1.5 in wt.%) were fabricated. The alloys were directionally solidified by Bridgman method under the same solidification condition at withd...
متن کاملFirst-principles Study of the Mechanical Properties of TiAl-Based Alloys
TiAl-based alloys have been suggested as advanced high-temperature structural materials replacing the Ni-based superalloys, due to their low density, high modulus, good oxidation resistance and creep resistance. However, their poor ductility and toughness at low temperature limits their applications in industry. Generally, controlling the microstructure and alloying elements are the most useful...
متن کاملInvestigation of the Heat Treatment Effect on Microstructures and Phases of Inconel 713C Superalloy
The application of Inconel 713C is very vast in different industries such as in automobiles, aircrafts, boilers and turbines. In this paper, Inconel 713C specimens were solutionized at 1000 and 1200 °C for 1 hours in order to study changes in phases and the structure of alloy to modify the γ' phase. The optical and the scanning electron microscopy were used to investigate the structure and the ...
متن کاملON THE FORMATION OF STRAY GRAINS IN DIRECTIONALLY-SOLIDIFIED NI-BASED SUPERALLOYS WITH VARYING CROSS SECTIONS
Formation of stray grain defects particularly around re-entrant features of the turbine blade airfoils is one of the major problems in directional and single crystal solidification processes. In this work, directional solidification tests of the GTD-111 Ni-based superalloy were conducted at different withdrawal velocities of 3, 6 and 9 mm.min-1 using various stepped cylindrical and cubic design...
متن کامل