Sushanta Kumar Panigrahi

Bio: Sushanta Kumar Panigrahi is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Alloy & Microstructure. The author has an hindex of 28, co-authored 81 publications receiving 2594 citations. Previous affiliations of Sushanta Kumar Panigrahi include Indian Institute of Technology Roorkee & École centrale de Nantes.

Thermal Stability, Grain Growth Kinetics, and Mechanical Properties of Bulk Ultrafine-Grained AA6063/SiC Composites with Varying Reinforcement Sizes

Abstract: Bulk ultrafine-grained (UFG) AA6063/4wt pct SiC composites with varying reinforcement sizes [12 µm (coarse), 1 µm (fine), and 45 nm (nano)] have been developed by a hybrid route of stir-casting and cryorolling. In the current study, the influence of annealing temperatures (423 K to 573 K) on the precipitation evolution, particle-stimulated nucleation (PSN), recrystallization, grain growth kinetics, and thermal stability of developed bulk UFG composites have been studied, and the resultant effect of microstructural evolution is correlated with mechanical properties. UFG coarse and UFG fine composites have shown evidence of recrystallized grains via PSN and retained their UFG microstructure up to 473 K and 523 K, respectively. Superior microstructural stability with retained UFG microstructure up to 573 K was observed in the UFG nanocomposite due to the effective pinning of nano-SiC particles and precipitates along grain boundaries. This ultimately resulted in the increased grain growth activation energy and strength of the UFG nanocomposite. However, the overall increase in strength is maximum in the UFG nanocomposite due to the dominant effect of dislocation strengthening, grain boundary strengthening, and precipitation strengthening mechanisms. A thorough examination of the microstructural evolution of UFG composites at different annealing temperatures along with their mechanical behavior is presented in this paper.

A comparative study on mechanical properties of ultrafine-grained Al 6061 and Al 6063 alloys processed by cryorolling

Abstract: The present work has been focused to investigate the mechanical behavior and microstructural characteristics of cryorolled Al 6063 and Al 6061 alloys. Hardness and tensile tests of the cryorolled Al alloys were carried out to understand its deformation behavior. SEM/EBSD was used to characterise the microstructures of cryorolled Al alloys and observed the formation of ultrafine-grained microstructures in the materials due to severe plastic strain induced during cryorolling. XRD was used to analyse the formation of different phases during cryorolling of the Al alloys. It is evident from the present study that UFG Al alloys exhibit higher hardness and strength when compared to the bulk Al alloys due to the grain size, higher dislocation density and precipitation hardening effect. The cryorolled Al 6061 alloys exhibit higher tensile strength (346 MPa) and hardness (120 Hv) as compared to Al 6063 alloys (Tensile strength: 240MPa and Hardness: 96.5 Hv) in the present investigation. The deformation mechanisms of UFG Al alloys contributing to their enhanced strength are discussed.

Microstructure dependent electroplastic effect in AA 6063 alloy and its nanocomposites

Abstract: The flow stress reduction during plastic deformation superposed with electric current, commonly referred as ‘electroplasticity’ has been actively researched over the past few decades. While the existence of an electron–dislocation interaction, independent of Joule heating is established, the exact rate controlling mechanism of the observed behaviour lacks consensus. Understanding the governing mechanism is complex due to the combined effect of Joule heating and electron–dislocation interaction. The present work attempts to establish the electroplastic mechanism in AA 6063 alloy and its nanocomposites. The role of microstructure on the electron interaction is investigated by preparing four distinct microstructure from the base alloy. All the samples were subjected to constant amplitude direct current during plastic deformation. The Joule heating effect is decoupled using the experimentally measured temperature history. The potential electroplastic mechanism for the alloy is elucidated by analysing the trend of flow stress reduction with strain and strain rate. It is inferred that micro Joule heating and electron wind effect cannot completely explain the observed electroplastic behaviour in AA 6063. The SiC particles in nano-composites suppressed the electroplastic effect. The observed mechanical behaviour under electric current is in agreement with the trend predicted assuming magnetic depinning mechanism. The reduction of dislocation density quantified using X-ray diffraction is found to concur with the inferred mechanism.

Achieving extraordinary structural efficiency in a wrought magnesium rare earth alloy

Abstract: The opportunities for wrought magnesium products in a wide range of structural and functional materials for transportation, energy generation, energy storage and propulsion are increasing due to th...

Nanostructured aluminium alloys produced by severe plastic deformation: New horizons in development

Abstract: In recent years, much progress has been made in the studies of nanostructured Al alloys for advanced structural and functional use associated both with the development of novel routes for the fabrication of bulk nanostructured materials using severe plastic deformation (SPD) techniques and with investigation of fundamental mechanisms leading to improved properties. This review paper discusses new concepts and principles in application of SPD processing to fabricate bulk nanostructured Al alloys with advanced properties. Special emphasis is placed on the relationship between microstructural features, mechanical, chemical, and physical properties, as well as the innovation potential of the SPD-produced nanostructured Al alloys.