• Anil K Bhatnagar

      Articles written in Bulletin of Materials Science

    • Thermoelectric behaviour of amorphous magnetic alloys

      B Bhanu Prasad Anil K Bhatnagar

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      The Thermoelectric emfs of thermocouples formed by amorphous METGLAS 2826 (Fe40Ni40P14B6) and METGLAS 2826B (Fe29Ni49P14B6Si2) with standard thermocouple wires like copper, chromel, alumel, etc., were measured as a function of temperature between −196° C and 30° C to assess their suitability as thermoelectric temperature sensors. Thermoelectric emfs generated by METGLAS 2826/Cu and METGLAS 2826B/Cu thermocouples at −196° C are about an order of magnitude smaller when compared to thermal emfs of a standard copper/constantan thermocouple at the same temperature.

    • Ferromagnetic resonance in metallic glasses: study of fracture, stress and thermal stability

      R S Parashar C S Sunandana Anil K Bhatnagar

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      Effects of fracture, stress and isothermal annealing of Fe-Ni based metallic glasses have been investigated using the ferromagnetic resonance technique.fmr linewidth is quite sensitive to changes in the magnetic and structural order in metallic glasses, andfmr lineshape seems to provide useful qualitative information on the mechanical state of these systems. Our observations are compared with recent work of Baianu and co-workers.

    • Magnetic properties of metallic glass Fe39Ni39Mo4Si6B12

      B Bhanu Prasad Anil K Bhatnagar S Venkataraman M N Chandrasekharaiah

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      Magnetic metallic glass Fe39Ni39Mo4Si6B12 has been studied by the57Fe Mössbauer spectroscopy. Mössbauer spectra consist of broad and overlapping six-line pattern below the Curie temperature. The Curie and crystallization temperatures of this metallic glass have been determined to be 575 ± 3 K and 725 ± 3 K, respectively. The hyperfine magnetic field at room temperature is approximately 225 kOe. The reduced hyperfine fields of this sample decrease much faster than that observed for other iron-rich metallic glasses like Fe40Ni40B20, Fe80B20 etc. This behaviour is attributed to the presence of molybdenum atoms in the sample.

    • Spin-wave excitations in amorphous ferromagnets

      Anil K Bhatnagar B Bhanu Prasad N Ravi R Jagannathan

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      Mössbauer measurements have been performed on a number of metallic glasses. The temperature dependence of average hyperfine or internal magnetic fieldHeff(T) arises from long wavelength spin wave excitations in these glasses. Values ofB3/2 andC5/2 are in general much higher than those observed for crystalline ferromagnets indicating higher density of states for spin waves in amorphous ferromagnets.

    • Crystallization and kinetics studies of Ti$_{20}$Zr$_{20}$Cu$_{60−x}$Ni$_x$ ($x = 10$, 20, 30 and 40) metallic glasses

      P RAMA RAO ANIL K BHATNAGAR BHASKAR MAJUMDAR

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      Synthesis and characterization of Ti$_{20}$Zr$_{20}Cu$_{60−x}$ Ni$_x$ ($x = 10$, 20, 30 and 40) metallic glasses are reported in this paper. Glassy ribbons are produced by rapid quenching using the standard copper wheel roller technique in argon atmosphere. Their structural characterization is carried out by X-ray diffraction (XRD) and thermal behaviour (crystallization) study by differential scanning calorimetry (DSC). Results of XRD on both sides of each ribbon sample confirmed that each sample was indeed amorphous/glassy as only a very broad peak in XRD pattern was observed. Metallic glass Ti$_{20}$Zr$_{20}$Cu$_{50}$Ni$_{10}$ shows three crystallization peaks in non-isothermal DSC scans while other three samples show only a single crystallization peak. The activation energy of crystallization for each sample has been calculated using three available models, namely, those of Kissinger, Augis–Bennett and Ozawa. All the three models gave nearly similar activation energies for a given sample within 10%.

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