Author
M. C. Chaturvedi
Bio: M. C. Chaturvedi is an academic researcher from University of Manitoba. The author has contributed to research in topics: Superalloy & Heat-affected zone. The author has an hindex of 25, co-authored 37 publications receiving 2581 citations.
Topics: Superalloy, Heat-affected zone, Liquation, Inconel, Eutectic system
Papers
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TL;DR: In this article, the constituents of nickel-base superalloys have been classified into solid solution formers, precipitate formsers, carbide formers and surface stabilizers, and the characteristics of solutes which would make them most suitable in each category have been specified and appropriate alloying elements have been identified.
Abstract: The constituents of nickel-base superalloys have been classified into solid solution formers, precipitate formers, carbide formers and surface stabilizers. The characteristics of solutes which would make them most suitable in each category have been specified and appropriate alloying elements have been identified. Nickel-base superalloys are hardened primarily by the precipitation of Ni3X type compounds. The occurrence and crystallography of precipitation of various kinds of Ni3X type precipitates have been considered. The role of substitution by alloying elements on mismatch and stability of phases has been discussed. The free electron model and the Engel-Brewer model have been applied for evaluating the stabilities of precipitates, and the role of the alloying elements in determining the stabilities of external and internal surfaces such as grain boundaries have been briefly outlined.
296 citations
TL;DR: The weld heat affected zone (HAZ) cracking in cast Inconel 738 superalloy has been examined in this article, where the main strengthening phase of the alloy c 0, which is also present in significant volume after pre-weld heat treatment, was found to contribute significantly to grain boundary liquation and its attendant cracking in the HAZ.
220 citations
TL;DR: In this article, the yielding behavior of underaged Inconel alloy 718, which is precipitation hardened by coherent ordered bct γ″ and ordered fcc γ′ phases, has been studied.
Abstract: The yielding behaviour of underaged Inconel alloy 718, which is precipitation hardened by coherent ordered bct γ″ and ordered fcc γ′ phases, has been studied. It was found that the yielding of the ...
174 citations
Book•
01 Dec 1991
TL;DR: In this article, phase stability interphase stabilisation interphase interfaces empirical transformation kinetics nucleation liquid-solid transformation diffusional transformation in solids short range diffusion, long range diffusion spinoidal decomposition martensitic transformation transformations in steel.
Abstract: Phase stability interphase stability interphase interfaces empirical transformation kinetics nucleation liquid-solid transformations diffusional transformation in solids short range diffusion, long range diffusion spinoidal decomposition martensitic transformation transformations in steel.
174 citations
TL;DR: The coarsening behavior of disc-shaped, ordered bct γ″-phase and spherical ordered fcc γ′-phase particles in Inconel alloy 718* has been studied in this article.
Abstract: The coarsening behaviour of disc-shaped, ordered bct γ″-phase, and spherical ordered fcc γ′-phase particles in Inconel alloy 718* has been studied. In the 973–1023 K temperature range, used in the ...
145 citations
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TL;DR: In this article, a classification of model-free isoconversion methods for the calculation of activation energies of thermally activated reactions is proposed, by deriving expressions for the main sources of error which includes the inaccuracy in reaction rate measurement, approximations for the temperature integral and inaccuracies in determination of temperature for equivalent fraction transformed.
1,393 citations
TL;DR: A critical review of work on the formation of precipitates and intermetallic phases in dilute precipitation hardening Al-Cu-Mg based alloys with and without Li additions is presented in this paper.
Abstract: The present study contains a critical review of work on the formation of precipitates and intermetallic phases in dilute precipitation hardening Al–Cu–Mg based alloys with and without Li additions. Although many suggestions for the existence of pre-precipitates in Al–Cu–Mg alloys with a Cu/Mg atomic ratio close to 1 have been made, a critical review reveals that evidence exists for only two truly distinct ones. The precipitation sequence is best represented as: supersaturated solid solution→co-clusters→GPB2/S"→S where clusters are predominantly Cu–Mg co-clusters (also termed GPB or GPB I zones), GPB2/S" is an orthorhombic phase that is coherent with the matrix (probable composition Al10Cu3Mg3) for which both the term GPB2 and S" have been used, and S phase is the equilibrium Al2CuMg phase. GPB2/S" can co-exist with S phase before the completion of the formation of S phase. It is further mostly accepted that the crystal structure of S' (Al2CuMg) is identical to the equilibrium S phase (Al2CuMg). Th...
719 citations
TL;DR: In this paper, the current knowledge on dislocation types and slip systems, the development of deformation substructures, factors controlling the mobility and multiplication of dislocations, interface related plasticity, solid solution and precipitate strengthening mechanisms as well as microscopic aspects of creep and fracture are addressed.
Abstract: During the past decade considerable research efforts have been directed towards achieving balanced engineering properties of two-phase γ-titanium aluminide alloys for future applications as structural materials. For optimization of mechanical properties such as yield and creep strengths, tensile ductility and fracture resistance, a basic understanding of the temperature dependent micromechanisms of plasticity and fracture, and their interplay with various microstructural constituents is required. In this review article, the current knowledge on dislocation types and slip systems, the development of deformation substructures, factors controlling the mobility and multiplication of dislocations, interface related plasticity, solid solution and precipitate strengthening mechanisms as well as microscopic aspects of creep and fracture will be addressed. These topics will be related to specific microstructures and associated engineering properties.
633 citations
TL;DR: In view of the interest attaching to the vaporisation and diffusion of solids, the following observations may be worthy of record as discussed by the authors, which may be seen as a good starting point for further research.
Abstract: IN view of the interest attaching to the vaporisation and diffusion of solids, the following observations may be worthy of record.
560 citations
TL;DR: Partial transient liquid phase (PTLP) bonding as discussed by the authors is a variant of TLP bonding that is typically used to join ceramics and has found many applications, most notably the joining and repair of Ni-based superalloy components.
Abstract: Transient liquid phase (TLP) bonding is a relatively new bonding process that joins materials using an interlayer. On heating, the interlayer melts and the interlayer element (or a constituent of an alloy interlayer) diffuses into the substrate materials, causing isothermal solidification. The result of this process is a bond that has a higher melting point than the bonding temperature. This bonding process has found many applications, most notably the joining and repair of Ni-based superalloy components. This article reviews important aspects of TLP bonding, such as kinetics of the process, experimental details (bonding time, interlayer thickness and format, and optimal bonding temperature), and advantages and disadvantages of the process. A wide range of materials that TLP bonding has been applied to is also presented. Partial transient liquid phase (PTLP) bonding is a variant of TLP bonding that is typically used to join ceramics. PTLP bonding requires an interlayer composed of multiple layers; the most common bond setup consists of a thick refractory core sandwiched by thin, lower-melting layers on each side. This article explains how the experimental details and bonding kinetics of PTLP bonding differ from TLP bonding. Also, a range of materials that have been joined by PTLP bonding is presented.
453 citations