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 , additively manufactured (AM) Ni-base alloy IN625 has been studied in air and Ar-5%H2-3% H2O at 900-1000 °C.
7 citations
TL;DR: The shape and the orientation of the precipitates were evaluated using the structure tensor, an operator that quantifies the directionality of the intensity distribution in an image to identify clusters of intragranular precipitates.
Abstract: This paper describes an image processing method for discriminating the inter- and intragranular delta phase precipitates in Inconel 718 (IN 718). The successive practical operations and the motivations of their choices are presented in detail. The method was applied to IN 718 specimens heat treated with different parameters to produce microstructures containing various amounts of both types of precipitates. They were characterized by electron microscopy in backscattered electron imaging. The main difficulty arose from the fact that the brightness distributions of inter- and intragranular precipitates partially overlap. Additional information on their morphology and their spatial distribution had to be exploited in order to differentiate them. The shape and the orientation of the precipitates were evaluated using the structure tensor, an operator that quantifies the directionality of the intensity distribution in an image. The distance between parallel precipitates was also used as an additional property to identify clusters of intragranular precipitates.
7 citations
TL;DR: In this article, a detailed study of microstructure and hardness of heat-affected zone (HAZ) was performed in both as-welded and aged state, and the results showed that the precipitation of δ phase, especially the intergranular δ, can lead to the enrichment of Nb and Mo elements, which promote the formation of γ/Laves eutectic constituent at grain boundaries in HAZ.
Abstract: The GH4169 superalloy with different content of δ-Ni3Nb phase was welded by tungsten inert gas welding. A detailed study of microstructure and hardness of heat-affected zone (HAZ) was performed in both as-welded and aged state. The results show that the precipitation of δ phase, especially the intergranular δ phase, can lead to the enrichment of Nb and Mo elements, which promote the formation of γ/Laves eutectic constituent at grain boundaries in HAZ. In as-welded state, the hardness decreases first and then increases (exhibiting a “V” shape) with distance away from fusion line in HAZ, which is governed by grain size. After aging treatment, however, the γ″ phase plays a key role in hardness and leads to the “Λ” shape profiles of hardness in HAZ.
7 citations
TL;DR: In this paper, an approach of simultaneous acquisition of two contact resonances and using the isotropic indentation modulus of matrix in every scan line as reference is used to circumvent the effect of change in tip condition while mapping elastic properties.
Abstract: The paper reports mapping of elastic properties of various precipitates such as γ′, δ, and carbides in nickel-base superalloys. Atomic force acoustic microscopy is used to measure the elastic properties with a lateral resolution of better than 100 nm in polycrystalline alloy 625 and directionally solidified alloy CM247A. A novel approach of simultaneous acquisition of two contact resonances and using the isotropic indentation modulus of matrix in every scan line as reference is used to circumvent the effect of change in tip condition while mapping elastic properties. Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy is performed to identify the precipitates and their compositions. Carbides exhibited highest modulus followed by δ precipitates, γ′ and γ matrix, respectively. It is demonstrated that due to the close-packed orientation relationships of precipitates with the matrix, the modulus of a precipitate measured by the methodology described in this study is not affected by the orientation of individual grain in which the measurement is made.
7 citations
TL;DR: In this paper, the effect of element Te on the alterations of microstructure and mechanical property of nickel-based superalloy Inconel 718 was studied and quantitatively characterized with scanning electron microscopy and energy dispersive X-ray spectroscopy.
7 citations
References
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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.
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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