Author
Rohit Trivedi
Other affiliations: Ames Laboratory
Bio: Rohit Trivedi is an academic researcher from Iowa State University. The author has contributed to research in topics: Directional solidification & Dendrite (crystal). The author has an hindex of 37, co-authored 97 publications receiving 6434 citations. Previous affiliations of Rohit Trivedi include Ames Laboratory.
Papers published on a yearly basis
Papers
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TL;DR: In this article, some of the fundamental factors which play important roles in determining microstructures under rapid solidification condition are described, and it is shown that the interface stability analysis needs to be extended to include the possibility of high thermal as well as high solute undercoolings.
901 citations
TL;DR: In this paper, the authors review the most important findings in this technologically important area that impact Our quantitative understanding of: (i) key anisotropic properties of the solid liquid interface that govern solidification pattern evolution, including the solid-liquid interface free energy and the kinetic coefficient; (ii) dendritic solidification at small and large growth rates.
612 citations
TL;DR: The status of solidification science is critically evaluated and future directions of research in this technologically important area are proposed in this paper, where the most important advances in solidification sciences and technology of the last decade are discussed: interface dynamics, phase selection, microstructure selection, peritectic growth, convection effects, multicomponent alloys, and numerical techniques.
535 citations
TL;DR: In this article, the theory of dendritic growth into undercooled alloy melts is extended to the case of large undercoolings, i.e. to high growth rates, by applying the results of the complete stability analysis of a plane interface to the tip of an Ivantsov dendrite.
517 citations
TL;DR: In this article, a theoretical model based on the Hunt model is developed, and it is found that the theory adequately explains the variation in primary spacing, λ 1, with the growth rate,V.
Abstract: The primary spacing data of Part I are compared to the existing theoretical models of Hunt and of Kurz and Fisher, and a significant disagreement is found. A theoretical model based on the Hunt model is developed, and it is found that the theory adequately explains the variation in primary spacing, λ1, with the growth rate,V. A maximum in λ1,vs V is predicted and the velocity at which the maximum occurs matches with the result obtained experimentally. It is shown that the maximum in λ1 corresponds to the dendrite-to-cell transition, and cellular structures are found to grow with much smaller spacings than dendritic structures under identical growth conditions.
355 citations
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TL;DR: A review of the emerging research on additive manufacturing of metallic materials is provided in this article, which provides a comprehensive overview of the physical processes and the underlying science of metallurgical structure and properties of the deposited parts.
4,192 citations
TL;DR: The phase-field method has recently emerged as a powerful computational approach to modeling and predicting mesoscale morphological and microstructure evolution in materials as discussed by the authors, which is able to predict the evolution of arbitrary morphologies and complex microstructures without explicitly tracking the positions of interfaces.
Abstract: ■ Abstract The phase-field method has recently emerged as a powerful computational approach to modeling and predicting mesoscale morphological and microstructure evolution in materials. It describes a microstructure using a set of conserved and nonconserved field variables that are continuous across the interfacial regions. The temporal and spatial evolution of the field variables is governed by the Cahn-Hilliard nonlinear diffusion equation and the Allen-Cahn relaxation equation. With the fundamental thermodynamic and kinetic information as the input, the phase-field method is able to predict the evolution of arbitrary morphologies and complex microstructures without explicitly tracking the positions of interfaces. This paper briefly reviews the recent advances in developing phase-field models for various materials processes including solidification, solid-state structural phase transformations, grain growth and coarsening, domain evolution in thin films, pattern formation on surfaces, dislocation microstructures, crack propagation, and electromigration.
2,334 citations
Journal Article•
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2,147 citations
01 May 1991-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In the limit of vigorous convection and slow cooling, grains become spheroidal and behave thixotropic, and viscosity can be varied over a wide range, depending on processing conditions as mentioned in this paper.
Abstract: During dendritic solidification of castings and ingots, a number of processes take place simultaneously within the semisolid region. These include crystallization, solute redistribution, ripening, interdendritic fluid flow, and solid movement. The dendritic structure which forms is greatly affected by convection during the early stages of solidification. In the limit of vigorous convection and slow cooling, grains become spheroidal. Alloys with this microstructure possess rheological properties in the semisolid state which are quite different from those of dendritic alloys. They behave thixotropically, and viscosity can be varied over a wide range, depending on processing conditions. The metal structure and its rheological properties are retained after solidification and partial remelting. The semisolid alloys can be formed in new ways, broadly termed «semisolid metal (SSM) forming processes». Some of these are now employed commercially to produce metal components and are also used to produce metal-matrix composites
1,365 citations
TL;DR: In this article, the authors reviewed the application of the phase-field method in different fields of materials science, including elastic interactions and fluid flow in multi-grain multi-phase structures in multicomponent materials.
Abstract: The phase-field method is reviewed against its historical and theoretical background. Starting from Van der Waals considerations on the structure of interfaces in materials the concept of the phase-field method is developed along historical lines. Basic relations are summarized in a comprehensive way. Special emphasis is given to the multi-phase-field method with extension to elastic interactions and fluid flow which allows one to treat multi-grain multi-phase structures in multicomponent materials. Examples are collected demonstrating the applicability of the different variants of the phase-field method in different fields of materials science.
1,004 citations