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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15 May 2010-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the Cozar and Pineau's model was used to predict the precipitation sequence of Alloy 718 microstructure in the case of specimens subjected to standard ageing treatment.
Abstract: Alloy 718 samples aged to precipitate only δ particles (with maximum volume fraction) when tensile deformed to fracture at elevated temperatures revealed precipitation of γ′ and γ″ phases. The γ′ precipitation was found to precede the γ″ phase precipitation unlike in the case of specimens subjected to standard ageing treatment where both the γ′ and the γ″ phases precipitate simultaneously. This sequence is explained on the basis of the relative concentration of Al, Ti and Nb in the matrix of δ precipitated Alloy 718 microstructure. The precipitation sequence was consistent with the Cozar and Pineau's model that predicts such sequences on the basis of (Al + Ti) to Nb atom ratios.
41 citations
30 Oct 2012-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: Inconel 718 powders were used as green compacts for pressureless sintering at temperatures of 1200, 1225, and 1250°C for 10, 60, and 180 min this article.
Abstract: The deposition of Inconel 718 powders, by cold spray, was performed on a mild steel substrate. The deposits showed a porosity level lower than 3%, but lacked interparticle bonding, hence strength. To circumvent the problem, the deposits were used as green compacts for pressureless sintering at temperatures of 1200, 1225, and 1250 °C for 10, 60, and 180 min. The grain size, second-phase distribution, micro-hardness, and flexural strength were measured. Upon sintering, the flexural strength and strain increased from 187±41 to 1225±122 MPa, and 0.026±0.022 to 0.183±0.037, respectively. After a conventional aging treatment, a maximal strength of 2303 MPa was obtained. During the sintering treatment, minimal grain growth occurred in the 1200 and 1225 °C trials where the calculated grain growth exponent was n =1/8. However for the sintering trials at 1250 °C, the grain growth exponent was found to be n =1/2. The grain growth was found to be influenced by secondary MC carbides that precipitated during the sintering treatment but dissolved at 1250 °C. The carbides acted as a pinning phase during the sintering treatment, explaining the reduced grain growth for the 1200 °C and 1225 °C conditions.
39 citations
TL;DR: In this paper, the effect of process temperature on microstructure evolution of electron beam melted Inconel 718 was investigated and the results showed that the fine grain boundary δ (∼200nm) along with coar...
Abstract: This study reports the effect of process temperature on microstructure evolution of electron beam melted Inconel 718. Samples fabricated at 915°C had fine grain boundary δ (∼200 nm) along with coar...
39 citations
TL;DR: In this article, the effect of composition on the APBE of Ni-base superalloys has been investigated using density functional theory-based cluster expansion calculations, and an empirical master equation has been derived based on the composition of the γ′ phases.
39 citations
TL;DR: In this article, the volume fraction of the δ-delta phase in cold-rolled Inconel 718 at 910 Cm for different time is measured by X-ray diffraction techniques, and the influence of cold rolling on the morphology and volume fraction is investigated.
38 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
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