Precipitation of the δ-Ni 3 Nb phase in two nickel base superalloys
01 Mar 1988-Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science (Springer-Verlag)-Vol. 19, Iss: 3, pp 453-465
TL;DR: In this article, the precipitation of the metastable δ-Ni3Nb phase has been studied in two niobium bearing nickel base superalloys and the morphology and distribution of precipitates have been examined and the crystallographic orientation relationship between the austenite and the δ phases has been determined.
Abstract: The precipitation of the equilibrium δ-Ni3Nb phase has been studied in two niobium bearing nickel base superalloys—INCONEL 718 and INCONEL* 625—both of which are hardenable by the precipitation of the metastableγ″-Ni3Nb phase. The morphology and the distribution of precipitates have been examined and the crystallographic orientation relationship between the austenite and theδ phases has been determined. The nucleation of theδ phase at stacking faults within pre-existing δ" precipitates has been discussed.
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TL;DR: In this article , the electronic and thermodynamic variation of the Ni3Nb phase with pressure in the range of 0-1200 GPa under hydrostatic pressure was investigated by DFT, and the results obtained by using the GGA-PW91 generalized function have the smallest error with the experimental value.
Abstract: The electronic and thermodynamic variation of the δ-Ni3Nb phase with pressure in the range of 0–1200 GPa under hydrostatic pressure was investigated by DFT. By comparing the nucleation phase γ with the transition phase γ", it is found that the magnitude of the stability of the three phases remains the same under 0–1200 GPa, and the difference between the stability of δ and γ" phases is small and both are larger than that of γ. This indicates that the δ phase has the precipitation law of γ→δ and γ″→δ under 0–1200 GPa under hydrostatic pressure. The calculated data show that the results obtained by using the GGA-PW91 generalized function have the smallest error with the experimental value, and the properties of energy, cell volume, density of states, differential charge, elastic constant and phonon of γ, γ" and δ phases are calculated after the convergence of each parameter, and the δ phase is a strongly anisotropic material and the most dense vibration at 4.8 and 6.6 THz frequencies and the heat capacity δ>γ ">γ relationship.
2 citations
TL;DR: In this article, a computational model was developed to predict solid-state phase transformation kinetics within mechanical parts during metal additive manufacturing processes using the thermal history of an additive manufacturing fabricated mechanical part, along with necessary thermodynamic data and kinetic information as inputs.
Abstract: A computational model was developed to predict solid-state phase transformation kinetics within mechanical parts during metal additive manufacturing processes. This model is a modified version of the Johnson-Mehl-Avrami model for non-isothermal phase transformations that can be applied to various material systems undergoing solid-state phase transformations. Using the thermal history of an additive manufacturing fabricated mechanical part, along with the necessary thermodynamic data and kinetic information as inputs, the model outputs the history of phase fraction evolution during the build process. The model was applied to an Inconel 718 part built by powder bed fusion and a Ti-6Al-4V part built by directed energy deposition. Microstructure characterization and mechanical testing were performed for the validation of the model.
2 citations
2 citations
TL;DR: In this article, the precipitation and dissolution behavior of δ phase at varied states including as cast, heat treated and thermal processed of GH4169G alloy, have been investigated.
Abstract: The precipitation and dissolution behavior of δ phase at varied states including as cast, heat treated and thermal processed of GH4169G alloy, have been investigated. The results indicated that δ phase existed in the vicinity of Laves phase and carbides with mainly the rod-like, needle-like morphology, and lath-like morphology because of the segregation of Nb in the interdendritic area. The amount of the δ phase decreased with the increase of the annealing temperature, and the dissolution rate increased with the increase of the annealing temperature. After initial holding of 2 h at 1020°C, the residual δ phase fully dissolved at 1140°C for 20min for the as-cast ingot. The minimum holding time for δ phase dissolution at 1020°C was 2h.
2 citations
TL;DR: In this paper , a computational model was developed to predict solid-state phase transformation kinetics within mechanical parts during metal additive manufacturing processes using the thermal history of an additive manufacturing fabricated mechanical part, along with necessary thermodynamic data and kinetic information as inputs.
Abstract: A computational model was developed to predict solid-state phase transformation kinetics within mechanical parts during metal additive manufacturing processes. This model is a modified version of the Johnson-Mehl-Avrami model for non-isothermal phase transformations that can be applied to various material systems undergoing solid-state phase transformations. Using the thermal history of an additive manufacturing fabricated mechanical part, along with the necessary thermodynamic data and kinetic information as inputs, the model outputs the history of phase fraction evolution during the build process. The model was applied to an Inconel 718 part built by powder bed fusion and a Ti-6Al-4V part built by directed energy deposition. Microstructure characterization and mechanical testing were performed for the validation of the model.
2 citations
References
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Book•
01 Jan 1958
TL;DR: The Handbook of Lattice spacings and structures of metals and alloys as discussed by the authors is a handbook of argumentative essay structure spacing and lattice plane model modified by the incorporation of thermodynamic functions appropriate to the f.c.
Abstract: For the best product experience, a Handbook of of argumentative essay structure spacing Lattice Spacings and Structures of Metals and Alloys ScienceDirect. Get this from a library! A handbook of lattice spacings and structures of metals and alloys. (W B Pearson) Acm metal). Vol. lattice plane model modified by the incorporation of thermodynamic functions appropriate to the f.c.c. Al—Ag solid zones in the alloys. W. B. Pearson, Handbook of Lattice Spacings. Structures of Metals and Alloys.
3,090 citations
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01 Jan 1962
TL;DR: Modern Physical Metallurgy as mentioned in this paper describes the fundamental principles of physical metallurgy and the basic techniques for assessing microstructure and provides a balanced coverage of properties, characterization, phase transformations, crystal structure, and corrosion not available in other texts.
Abstract: Modern Physical Metallurgy describes, in a very readable form, the fundamental principles of physical metallurgy and the basic techniques for assessing microstructure This book enables you to understand the properties and applications of metals and alloys at a deeper level than that provided in an introductory materials course The eighth edition of this classic text has been updated to provide a balanced coverage of properties, characterization, phase transformations, crystal structure, and corrosion not available in other texts, and includes updated illustrations along with extensive new real-world examples and homework problems It offers renowned coverage of metals and alloys from one of the world's leading metallurgy educators It covers new materials characterization techniques, including scanning tunneling microscopy (STM), atomic force microscopy (AFM), and nanoindentation It provides the most thorough coverage of characterization, mechanical properties, surface engineering and corrosion of any textbook in its field It includes new worked examples with real-world applications, case studies, extensive homework exercises, and a full online solutions manual and image bank
421 citations
TL;DR: In this article, a review of theoretical models applicable to concentrated solid solutions is presented, focusing on concentrated solutions because dilute ones can be considered as special cases and because the interesting effects of clustering and ordering are most apparent at high solute concentrations.
Abstract: Publisher Summary This chapter reviews current theoretical models applicable to concentrated solid solutions. It focuses on concentrated solutions because dilute ones can be considered as special cases and because the interesting effects of clustering and ordering are most apparent at high solute concentrations. The extended ranges of solubility are often found in metallic systems, and for this reason most examples selected will refer to metals and alloys, although the models presented are equally applied to off-stoichiometric compounds, metallic or inorganic, and to amorphous solids. The chapter provides description of the state of the order of the system through suitable averaging procedures. It discusses the internal energy of solutions, from both electronic and elastic standpoints. The chapter presents free energy models, such as generalized Bragg- Williams's model, Landau theory, and cluster variation method. These models are applied to the study of phase equilibrium.
308 citations
01 Jan 1971-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this article, a heat treatment for 706 alloy was developed which effectively optimizes the 1200°F stress-rupture properties of the alloy by precipitation of globular to plate-like Ni3Cb/Ni3Ti at the grain boundaries in conjunction with maintaining a fine as-forged grain structure.
Abstract: Evaluation of a commercial heat treatment for 706 alloy indicated that it resulted in relatively low 1200° F stress rupture ductility. It was determined that this was caused by a solution treatment which dissolved all of the age-hardening phases in the alloy and caused a coarse grain size and supersaturated matrix condition. Based upon extensive fine structure study of the 706 alloy as well as previous experience with 718 alloy and other Fe−Ni-base superalloys, a heat treatment is developed which effectively optimizes the 1200°F stress-rupture properties of the alloy. The key to best properties was found to be the precipitation of globular to plate-like Ni3Cb/Ni3Ti at the grain boundaries in conjunction with maintaining a fine as-forged grain structure.
44 citations