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Journal ArticleDOI

Precipitation of the δ-Ni 3 Nb phase in two nickel base superalloys

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.
Citations
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Journal ArticleDOI
TL;DR: In this paper, high cycle fatigue behavior of the superalloy IN718 was studied in the air at 600°C in fully reversed stress controlled mode (R = −1), in the as heat treated condition as well as pre hot corroded in the salt mixture of 75Na2SO4+15NaCl+10V2O5 (wt.%) at 600 °C for 100

21 citations

Journal ArticleDOI
TL;DR: In this paper, Roberts et al. used the diamond light source for beam time provisioning, which was provided through the EPSRC/Rolls-Royce strategic partnership EP/M005607/1 and EP/H022309/1.
Abstract: The authors would like to thank K. Roberts and S. Rhodes for experimental assistance, and acknowledge funding through the EPSRC/Rolls-Royce strategic partnership EP/M005607/1 and EP/H022309/1 as well as from the Diamond Light Source for the provision of beam time (EE9270).

21 citations

Journal ArticleDOI
TL;DR: The microstructures and mechanical properties of Nb modified Nimonic 80A were investigated in this paper, where Nb increases the precipitate temperature and weight fraction of γ-Ni 3 Nb phase and exhibits an orientation relationship with the blocky (Nb, Ti)C at 845°C.
Abstract: The microstructures and mechanical properties of Nb modified Nimonic 80A were investigated. Nb increases the precipitate temperature and weight fraction of γ′ phase. The substitution of Ti by Nb and the precipitate of (Nb, Ti)C lead to the decrease of Ti composition in γ′ phase after full heat treatment. The diffusion of Nb from γ to γ′ phase makes part of the fine γ′ 2 particles coexist with the coarse γ′ 1 particles. The δ-Ni 3 Nb phase precipitates in γ matrix channel and exhibits an orientation relationship with the blocky (Nb, Ti)C at 845 °C: (100) δ ‖ (100) MC and [010] δ ‖ [010] MC . Precipitate of (Nb, Ti)C in γ matrix channel and at grain boundaries suppresses γ′ coarsening and grain boundary sliding, respectively. The (Nb, Ti)C precipitated at grain boundary also suppresses the coalescence of cavities at high temperature. The stress-rupture life of the 1.5 wt% Nb modified Nimonic 80A increases by about 25.4% at 750 °C/310 MPa and the creep life increases from less than 500 h to more than 1300 h at 750 °C/240 MPa. The diffusion of Nb element into γ′ phase and the precipitates of carbides significantly improve the mechanical properties of Nimonic 80A.

21 citations

Journal ArticleDOI
TL;DR: In this paper, the precipitation behavior of Alloy 625 and Alloy 625 Plus after thermal aging at 650°C up to 1000 h were quantitatively compared and it was shown that Alloy 625 plus exhibited higher number density and volume fraction and a slower coarsening rate of γ″ precipitates.

20 citations

Journal ArticleDOI
TL;DR: The specific heat capacity of Alloy-718 and Udimet-alloy 720 was measured using a differential scanning calorimeter in the temperature range of 100 − 1000 K as mentioned in this paper.
Abstract: Alloy-718 and Udimet alloy 720 are gamma prime strengthened superalloys with excellent mechanical and thermal properties at elevated temperatures, as well as at cryogenic temperatures. The nickel-based alloys were improved to be resistant to creep and become stronger by changing the heat-treatment conditions. The measurement of the specific heat capacity of a nickel-based alloy is a very useful tool to investigate the effect of heat treatment. The specific heat capacity of nickel-based alloys Alloy-718 and Udimet alloy 720 were measured using a differential scanning calorimeter in the temperature range of 100 – 1000 K. The specific heat capacity of the nickel-based alloys increases monotonically with temperature; however, above 800 K, it is strongly dependent on the heat treatment conditions and it is thought to be influenced by the precipitation phase (γ′, γ′′). Optical and scanning electron microscopies are used to investigate the microstructure of the phases. The microstructures of the precipitates are examined.

20 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

Book ChapterDOI
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

Journal ArticleDOI
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