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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01 Feb 2023-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article , hot-rolled Inconel 718 alloys were subjected to three different heat treatment schedules to develop various precipitated phases (γ″ phase, γ′ phase, needle-shaped phase, and granular δ phase).
Abstract: In this study, hot-rolled Inconel 718 alloys were subjected to three different heat treatment schedules to develop various precipitated phases (γ″ phase, γ′ phase, needle-shaped δ phase, and granular δ phase). Based on microstructural characterization and mechanical testing, the effects of these precipitated phases on the mechanical properties and fracture mechanisms were investigated. The results showed that a double-aging treatment process was the key to ensuring the complete precipitation and growth of the γ″ and γ′ phases. A small amount of δ phase (∼2.5%) precipitating in the solution treatment stage did not affect the precipitation of the γ″ and γ′ phases in the subsequent aging treatment stage. An Inconel 718 alloy without δ phase precipitation had excellent impact toughness, and the fracture mode was ductile fracture caused by dislocation slip separation. However, if it was present, the morphology of δ phase determined the effect on the impact toughness. The fracture mechanism changed from a mixed fracture mode of intergranular and transgranular fracture to quasi-cleavage fracture when the morphology of the precipitated δ phase was transformed from needle-shaped to granular-shaped. According to the theory of the dihedral angle (2θ) for precipitated phase morphologies, a quantitative relationship between the interfacial energies of the needle-shaped δ phase and granular δ phase was determined. The interfacial energy of the needle-shaped δ phase was only ∼76% of that of the granular δ phase, meaning that the needle-shaped δ phase was likely to debond readily from the matrix, resulting in the formation of intergranular cracks.
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TL;DR: In this paper, a two-stage aging treatment with different initial loading stresses were carried out in the Inconel 718 alloy after solution annealing process to investigate the stress relaxation and age hardening behaviors on basis of microstructural evolution.
Abstract: The two-stage aging treatment with different initial loading stresses were carried out in the Inconel 718 alloy after solution annealing process to investigate the stress relaxation and age hardening behaviors on basis of microstructural evolution. The result showed that the stress relaxation behavior mainly occurred in the first aging stage and the corresponding mechanism changed from diffusion creep with initial loading stress of 100 MPa into dislocation slip with initial stress of 600 MPa. Simultaneously, the influence of initial stress on yield strength was counteracted balanced the creep recovery and dislocation hardening, resulting in nearly constant value if yield strength. During the secondary aging stage, the strength of the purely aged sample is 3% higher than that of the high initial stress sample, and the precipitated phase morphology distribution is more uniform. The stress relaxation occurred in the secondary aging stage was negligible, irrespective of initial stress status. In condition, the application of initial stress gave rise to the precipitation behavior, which presented faster growth and coarsening with increasing initial stress value. As a comparison, the distribution of precipitates in sample without loading stress relatively more homogeneous and revealed denser, leading to higher yield strength compared with other samples with initial stress.
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TL;DR: In this paper , the effects of the temperature and time of aged treatment on the secondary phase evolutions, tensile properties, and strengthening mechanism of Inconel 625 superalloy were systematically investigated.
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06 Jan 2020
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Dissertation•
14 May 2019
TL;DR: In this paper, the authors present a collection of tables, columns, and figures from the paper "Thesis Layout: A LITERATURE this paper : A Review of Thesis Layout".
Abstract: .................................................................................................................................. vi LIST OF TABLES ......................................................................................................................... xi LIST OF FIGURES ...................................................................................................................... xii CHAPTER 1 – INTRODUCTION ................................................................................................. 1 1.1 Background Information .................................................................................................. 1 1.2 Research Objective ........................................................................................................... 6 1.3 Work Done ....................................................................................................................... 6 1.4 Major Findings ................................................................................................................. 6 1.4 Thesis Layout ................................................................................................................... 8 CHAPTER 2 LITERATURE REVIEW ....................................................................................... 9 2.
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Additional excerpts
...In IN 718 alloy, the morphology of δ phase has been reported to be plate-like [54],[55] while other investigators have...
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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
Book•
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