• M Chakraborty

      Articles written in Bulletin of Materials Science

    • Separation of matrix alloy and reinforcement from aluminum metal matrix composites scrap by salt flux addition

      K R Ravi R M Pillai B C Pai M Chakraborty

      More Details Abstract Fulltext PDF

      Separation of matrix alloy and reinforcements from pure Al–SiCp composite scrap by salt flux addition has been theoretically predicted using interface free energies. Experiments performed confirm the theoretical prediction. Complete separation of matrix aluminum and reinforcement from metal matrix composites (MMCs) scrap has been achieved by addition of 2.05 wt% of equimolar mixture of NaCl–KCl salt flux with a metal and particle yield of 84 and 50%, respectively. By adding 5 wt% of NaF to equimolar mixture of NaCl–KCl, metal and particle yield improved to 91 and 73%, respectively. Reusability of both the matrix aluminum and the SiC separated from Al–SiCp scraps has been analysed using XRD, SEM and DTA techniques. The matrix alloy separated from Al–SiCp scraps can be used possibly as a low Si content Al–Si alloy. However, the interfacial reaction that occurred during the fabrication of the composites had degraded the SiC particles.

    • Influence of melt treatments and polished CVD diamond coated insert on cutting force and surface integrity in turning of Al–7Si and Al–7Si–2.5Cu cast alloys

      K G Basavakumar P G Mukunda M Chakraborty

      More Details Abstract Fulltext PDF

      The microstructures, machinability and surface characteristics of Al–7Si and Al–7Si–2.5Cu cast alloys were studied after various melt treatments like grain refinement and modification. The results indicate that combined grain refined and modified Al–7Si–2.5Cu cast alloys have microstructures consisting of uniformly distributed 𝛼-Al grains, eutectic Al-silicon and fine CuAl2 particles in the interdendritic region. These alloys exhibited better machinability and surface characteristics in the cast condition compared with the same alloy subjected to only grain refinement or modification. Performances of the turning inserts (uncoated and polished CVD diamond coated) were evaluated in machining Al–7Si and Al–7Si–2.5Cu cast alloys under dry environment using a lathe. The polished CVD diamond coated insert outperformed the uncoated cutting insert which suffered from sizeable edge buildup leading to higher cutting force and poor surface finish. The polished CVD diamond coated insert shows a very small steady wear without flaking of the diamond film during cutting. This paper attempts to investigate the influence of grain refinement, modification and combined action of both on the microstructural changes in the Al–7Si and Al–7Si–2.5Cu cast alloys and their machinability and surface finish when different turning inserts are used.

    • Effect of melt treatment on microstructure and impact properties of Al–7Si and Al–7Si–2.5Cu cast alloys

      K G Basavakumar P G Mukunda M Chakraborty

      More Details Abstract Fulltext PDF

      The microstructures and impact toughness of Al–7Si and Al–7Si–2.5Cu cast alloys were studied after various melt treatments like grain refinement and modification. The results indicate that combined grain refined and modified Al–7Si–2.5Cu alloys have microstructures consisting of uniformly distributed 𝛼-Al grains, interdendritic network of fine eutectic silicon and fine CuAl2 particles in the interdendritic region. These alloys exhibited improved impact toughness in as cast condition when compared to those treated by individual addition of grain refiner or modifier. The improved impact toughness of Al–7Si–2.5Cu alloys are related to breakage of the large aluminum grains and uniform distribution of eutectic silicon and fine CuAl2 particles in the interdendritic region resulting from combined refinement and modification. This paper attempts to investigate the influence of microstructural changes in the Al–7Si and Al–7Si–2.5Cu cast alloys by grain refinement, modification and combined action of both on the impact toughness.

    • On the microstructure and interfacial properties of sputtered nickel thin film on Si (1 0 0)

      B Geetha Priyadarshini S Aich M Chakraborty

      More Details Abstract Fulltext PDF

      Ni films of thickness ranging from 150 to 250 nm were deposited by DC magnetron sputtering on to Si (100) substrates maintained at room temperature and followed by post-annealing at 300 and 500 °C for 30 min. Other set of Ni films were deposited on to Si (1 0 0) substrates held at annealing temperature of 300 and 500 °C for 30 min. Microstructural investigation by field emission scanning electron microscope (FE-SEM) and atomic force microscope (AFM) revealed columnar morphology with voided boundaries for films deposited at room temperature and was retained after post-deposition annealing at higher temperatures. Nickel silicide formation with isosceles triangle diffusion front was confirmed by cross-sectional highresolution transmission electron microscopy (X-HRTEM) for post-annealed Ni films. Thin film deposited at high substrate temperatures having near-equiaxed structure found to be the best route to fabricate thin films without silicide formation.

  • Bulletin of Materials Science | News

    • Dr Shanti Swarup Bhatnagar for Science and Technology

      Posted on October 12, 2020

      Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
      Chemical Sciences 2020

      Prof. Surajit Dhara — School of Physics, University of Hyderabad, Hyderabad
      Physical Sciences 2020

    • Editorial Note on Continuous Article Publication

      Posted on July 25, 2019

      Click here for Editorial Note on CAP Mode

© 2021-2022 Indian Academy of Sciences, Bengaluru.