Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 99 for “"Superalloys"”.
-
Hierarchical multiscale modeling of Ni-base superalloys
Ni-base superalloys are widely used in hot sections of gas turbine engines due to the high resistance to fatigue and creep at elevated temperatures. Due to the demands for improved performance and efficiency in applications of the superalloys, new and improved higher temperature alloy systems are …
-
Banding in nickel-base superalloys and steels
Process irregularities in remelting furnace operation have an impact on the ingot solidification structure which depends on the local thermal conditions and the alloy concerned. In this work, a laboratory investigation into the structures resulting from interruptions in solid growth is presented in …
-
Fatigue life prediction on nickel base superalloys
Neural networks have been used extensively in material science with varying success.It has been demonstrated that they can be very effective at predicting mechanical properties such as yield strength and ultimate tensile strength. These networks require large amounts of input data in order to learn …
-
Recrystallisation in Single Crystal Nickel-Based Superalloys
… investment casting of single crystal Ni-based superalloys arise from differences in thermal contraction between the metal and ceramic mould-and-core. If deformation is above a critical limit, subsequent solution heat treatment of the alloy causes recrystallisation. Crack nucleation and …
-
Plasticity of nickel base single crystal superalloys
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1995.
-
Composition effects on macroscopic solidification segregation of superalloys
… macrosegregation, i.e. freckles, in superalloys. First, the freckling mechanism of superalloys is developed using the physical simulation of freckle formation in specially designed model alloys. It is found that freckles originate from dendrite irregularities at the solidification …
-
Modelling of thermo-mechanical fatigue behavior in superalloys
Thermo-mechanical fatigue (TMF) and isothermal fatigue (IF) behavior of coated and uncoated Mar-M247 and, uncoated Mar-M246 was studied. The Mar-M247 was coated with Alpak-S1. The coating consists of a manganese and Aluminium powder slurry that is applied by painting, dipping, or spraying with an …
-
Atomistic modelling of precipitation in Ni-base superalloys
… phase ($\text{Ni}_{3}\text{Al}$) in Ni-base superalloys is fundamental to the performance of engineering components such as turbine disks and blades which operate at high temperatures and loads. Hence for these alloys it is important to optimize their microstructure and phase composition. …
-
Enhancing hot tooling to forge high-γ ′ superalloys
High-γ ′ nickel superalloys are increasingly employed in aircraft turbines for their remarkable high-temperature properties to enhance engine efficiency and reduce aviation emissions. These alloys are forged at temperatures approaching 1100 °C and require careful selection of process parameters to …
-
Thermal-mechanical fatigue behavior of nickel-base superalloys
Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1986.
-
Interdiffusion Analysis For Nicocraly And Nial Vs. Various Superalloys
… rate of Al interdiffusion into selected Ni-base superalloys using various diffusion couples of two-phase NiCoCrAlY (beta + gamma) and single beta-phase NiAl with the selected alloys is measured. The diffusion couples were examined with an emphasis on the composition-dependence of Al …
-
Simulation of creep in nickel based single crystal superalloys
Nickel based single crystal Superalloys are finding wide spread use in high temperature gas turbines and other similar applications because of their superior high-temperature strength and creep properties as compared to the other materials. This is due to two factors: solid solution and …
-
Understanding forgeability in highly reinforced cast-and-wrought superalloys
… γ′-reinforced cast-and-wrought nickel-based superalloys. The theory postulates that surface cracking is controlled by the dissolution of the secondary γ′ phase and its subsequent reprecipitation as very fine precipitates upon cooling. The commercial alloy Udimet 720 is used as a benchmark to …
-
Hydrogen embrittlement of selected nickel and iron-base superalloys
Made available in DSpace on 2011-05-07T14:12:15Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9114264.pdf: 8376451 bytes, checksum: 0a2e91e90f19192aa850c4cce03a90fe (MD5) Previous issue date: 1990
-
Stability of nickel-base superalloys for turbine disc applications
… beyond the capabilities of current nickel-base superalloys. As a result, new alloy compositions for turbine disc applications are being developed. Optimising these alloy compositions requires balancing directly competing requirements. Increased Cr contents are needed to provide environmental …
-
Computer simulation of carburization corrosion of nickel-base superalloys
… to simulate the corrosion behavior of Ni-based superalloys in carburizing atmospheres. The model is based on Crank-Nicholson finite difference solution of the diffusion equation. The code also includes the ternary cross diffusion effect due to substitutional alloying elements that are …
-
Investigation of lattice mismatch in rhenium containing nickel-base superalloys
In this study, three techniques for measuring gamma/gamma prime lattice mismatch were examined on two alloys, each of which had two different ageing heat treatments, i.e. standard age and overaged. Each alloy contained a different Re content so that the effect of this element on lattice mismatch …
-
Influence of surface hardening on single crystal nickel-based superalloys
… microstructures of single crystal nickel-based superalloys. These alloys have excellent high temperature properties, and consist of a randomly substituted face centred cubic matrix phase known as γ, together with a large volume fraction of an ordered precipitate phase, most often the primitive …
-
Understanding the Yield Behaviour of Single Crystal Ni-based Superalloys
Nickel-based superalloys are the material of choice for turbine applications due to their superior high-temperature strength capabilities. This has been attributed to the γ' precipitates which have the L1₂-ordered crystal structure. Because of the ordered crystal structure, dislocations must travel …
Page 1 of 5