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113 results on '"Bera, Supriya"'

13. Face-centered-cubic titanium in Ti/Al multilayer thin films synthesized by magnetron sputtering technique

Author

Rajagopalan, Ramaseshan, Dasgupta, Arup, Divakar, Ramachandran, Dash, Sitaram, Ravindran, Nithya, Saibaba, Saroja, Tyagi, Ashok Kumar, Bera, Supriya, and Manna, Indranil

Subjects
Condensed Matter - Materials Science, Condensed Matter - Other Condensed Matter
Abstract

Ti/Al multilayer thin films with precise thickness have been deposited using a combination of dc and rf magnetron sputtering techniques. Cross-sectional transmission electron microscopy (TEM) revealed unmixed fifteen parallel and alternate layers of Ti and Al with sharp interfaces, each measuring 27 nm and 15 nm in thickness, respectively. The Ti layer was composed of hcp and fcc phases while the Al layer was fcc. Both x-ray diffraction (XRD) and selected area electron diffraction (SAED) analysis confirmed the identity of these phases. Detection of fcc-Ti in as-deposited the Ti/Al multilayer thin film by XRD established that the fcc-Ti phase is not an artifact of TEM sample preparation, as have been envisaged by some of the previous researchers. The fcc-Ti phase appeared when dual rf guns were used for Ti deposition and the diffraction peak intensity corresponding to fcc phase increased when the gun power was raised. A modified equation of state based thermodynamic analysis confirmed that the formation of hcp phase as opposed to the thermodynamically stable fcc phase of pure Ti is due to crystallite size reduction and not impurity driven., Comment: 20 pages, 5 figures. Submitted to Journal of Applied Physics

Published
2009

18. Thermally Derived Hydroxyapatite from Nibea soldadoFish Bones Within Magnesium Matrix: Processing and Mechanical Behaviour

Author

De, Bipasha, Ghosh, Debanjana, Saha, Subhasis, Seikh, Ziyauddin, Das, Sagar, Bera, Supriya, Mandal, Gurudas, and Sinha, Arijit

Abstract

Fish waste has now emerged as one of the major issues encountered by the world, and improper management of its disposal might cause substantial environmental damage and nutrient loss. These wastes have a lot of potential if collected because they include a variety of biological and nutritional elements. Many bioactive and useful chemicals can be recovered from these wastes thanks to recent technical advancements. By-products from the processing of sea food contain many bioactive compounds, which has encouraged the development of ways for extracting these chemicals value. With the appropriate attitude and future advancement, fish waste processing for reuse and bioconversion has a bright future. In view of this, HAp (hydroxyapatite) can be extracted from fish wastes through a simple controlled heat treatment schedule and then used as potential candidate as dispersing phase within magnesium (Mg) matrix. HAp dispersed Mg composites containing 0,3,6, 9, 12 along with 15 wt% of HAp have been fabricated by powder metallurgical (P/M) approach. It is worthwhile to mention here that the P/M approach offers near-net-shape products, low power consumption, good control over density, simplicity of operation, as well as zero scrap over the casting technique which consume more energy as well as results in loss materials. A detailed investigation has been done into the morphological features, structural and mechanical characterization. XRD technique displays the evolution of bi-phasic phases viz.,HAp and β-TCP in the heat-treated fish wastes at around 1000 °C. The mechanical characteristics of the composites show increment in its values with the inclusion of HAp within Mg matrix. The present investigation displays a significant improvement in the microhardness (~ 525.4 MPa) of the Mg matrix on incorporation of 9 wt% of HAp content as compared to other content.

Published
2024
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34. Micropatterning kinetics of different glass-forming systems investigated by thermoplastic net-shaping

Author

Sarac, Baran, Bera, Supriya, Spieckermann, Florian, Balakin, Sascha, Stoica, Mihai, Cǎlin, Mariana, Eckert, Jürgen, and Publica

Subjects
formability kinetics, thermophysical properties, supercooled liquid fragility, thermoplastic net-shaping, glass-forming ability
Abstract

The formability difference between good and marginal glass-forming systems is investigated by micro-surface patterning of hierarchical features using thermoplastic net-shaping (TPN). For each alloy, a remarkable change in the flow behaviour is observed as the applied force along with the pressing time and temperature are optimized. The flow kinetics of glassy alloys with different glass-forming abilities is best described by the formability parameter S, which is defined by the ratio of the width of the supercooled to undercooled liquid region (Tl − Tg)/(Tx − Tg). Reproducible micro-engineered surfaces with high uniformity can be established by controlled TPN processing.

Published
2017

36. The Influence of Partial Replacement of Cu with Ga on the Corrosion Behavior of Ti40Zr10Cu36Pd14 Metallic Glasses.

Author

Qi Wei, Gostin, Petre Flaviu, Addison, Owen, Reed, Daniel, Calin, Mariana, Bera, Supriya, Ramasamy, Parthiban, and Davenport, Alison

Subjects
METALLIC glasses, CORROSION potential, MELT spinning, MOLDS (Casts & casting), PITTING corrosion, DENTAL implants
Abstract

TiZrCuPdGa metallic glasses are under consideration for small dental biomedical implants. There is interest in replacing some of the Cu with Ga to improve the glass-forming ability and biocompatibility. Ti40Zr10Cu36-xPd14Gax (x = 0, 1, 2, 4, 8 and 10 at.%) metallic glasses in rod and ribbon forms were fabricated by mould casting and melt spinning, respectively, and electrochemically tested in a 0.9wt.% NaCl (0.154 M) solution. It has been shown that for both rod and ribbon samples Ga levels up to 8% have no significant effect on passive current density, pitting potential or cathodic reactivity in 0.9% NaCl at 37°C. Different pitting potential and corrosion potential values were found when ribbon and rod samples of the same composition were compared for all compositions apart from the one containing the highest Ga level (10%). This was attributed to structural relaxation occurring as a result of the slower cooling rates during casting rods compared with melt-spinning ribbons. Substitution of Ga for Cu in these metallic glasses therefore expected to have no significant effect on corrosion susceptibility. [ABSTRACT FROM AUTHOR]

Published
2019
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50. Effect of High Tensile Strain Rate on the Evolution of Microstructure in Fe-Mn-C-Al Twinning-Induced Plasticity (TWIP) Steel.

Author

Das, Tuhin, Bera, Supriya, Saha, Rajib, Dahmen, Kirsten, Bleck, Wolfgang, Ghosh, Mainak, Chowdhury, Sandip, and Haldar, Arunansu

Subjects
STEEL, TENSILE strength, STRAIN rate, DEFORMATIONS (Mechanics), MICROSTRUCTURE, ELECTRON diffraction, RECRYSTALLIZATION (Metallurgy)
Abstract

Fe-17.8Mn-0.52C-0.5Al TWIP steel has been investigated under high-strain rate conditions. Twinning along with stacking faults and high dislocation densities in the austenite matrix has been evaluated by X-ray diffraction line profile analysis and transmission electron microscopy. The samples strained at 100 s show a gradient in the evolution of the dislocation density along the gage length except the fracture end where the density shows a decrease. In case of the samples strained at 1 s, the evolution of density shows attainment of a near-saturation stage. Electron backscatter diffraction analysis shows that the decrease in the dislocation density as well as near-saturation stage is due to dynamic recovery as well as dynamic recrystallization at region near the fracture end. The dynamically recrystallized grains are related to the deformed matrix through twin relationship. [ABSTRACT FROM AUTHOR]

Published
2015
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