• S K Chattopadhyay

      Articles written in Bulletin of Materials Science

    • An X-ray diffraction study of defect parameters in a Ti-base alloy

      G Karmaker P Mukherjee A K Meikap S K Chattopadhyay S K Chatterjee

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      Detailed studies based on the well established method of Fourier line shape analysis have been made on the X-ray diffraction profile of hexagonal titanium alloy of nominal composition Ti–6.58% Al–3.16% Mo–1.81% Zr–0.08% Fe–0.012% N–0.0078% C. While deformation fault probability, 𝛼, has been found to be quite high compared to that of pure titanium, the deformation growth fault parameter, 𝛽, shows a negative value ruling out the presence of growth fault in this alloy in the deformed state.

    • Effect of alloying with zinc on SFE of aluminium by study of lattice imperfections in cold worked Al–Zn alloys

      G Karmakar R Sen S K Chattopadhyay A K Meikap S K Chatterjee

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      A detailed X-ray Fourier line shape analysis has been performed on three compositions of Al–Zn alloys viz. Al–3 55 wt% Zn, Al–14 7 wt% Zn and Al–19 3 wt% Zn in fcc phase. It has been found that deformation stacking faults, both intrinsic 𝛼' and extrinsic 𝛼'' are absent in the cold worked state and twin fault 𝛽 is found to be slightly present in the deformed lattice of the two initial compositions of the alloys. Similar to the effect of solute germanium and copper, respectively in Al–Ge and Al–Cu systems, hexagonal zinc also fails to impart faulting in fcc Al–Zn system. This corroborates the fact that aluminium has high stacking fault energy.

    • Microstructural studies on variation of defect parameters in Zr–Sn alloys and their transition with interchange of solvent and solute in Zr–Ti and Ti–Zr alloy systems by modified Rietveld method and Warren–Averbach method

      J Ghosh S K Chattopadhyay A K Meikap S K Chatterjee

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      The effects of deformation and the transition of microstructural defect states with the interchange of solvent and solute in Ti–Zr and Zr–Ti alloys of six different compositions and Zr–Sn alloys in three different compositions have been investigated by X-ray diffraction line profile analysis. The detailed analysis of the X-ray powder diffraction line profiles was interpreted by Fourier line shape analysis using modified Rietveld method and Warren–Averbach method taking silicon as standard. Finally the microstructural parameters such as coherent domain size, microstrains within domains, faulting probability and dislocation density were evaluated from the analysis of X-ray powder diffraction data of Zr base Sn, Ti and Ti base Zr alloys by modified Rietveld powder structure refinement. This analysis confirms that the growth fault, 𝛽, is totally absent or negligibly present in Zr–Ti, Ti–Zr and Zr–Sn alloy systems, because the growth fault, 𝛽, has been observed to be either negative or very small for these alloy systems. This analysis also revealed that the deformation fault, 𝛼, has significant presence in titanium-base zirconium alloy systems but when zirconium content in the matrix goes on increasing beyond 50%, this faulting behaviour suffers a drastic transition and faulting tendency abruptly drops to a level of negligible presence or zero. This tendency has also been observed in Zr–Sn alloys signifying high stacking fault energy. Therefore, Zr and Zr-base alloys having high stacking fault energy can be used as hard alloys in nuclear technology at high temperature.

    • Study of microstructure in vanadium–palladium alloys by X-ray diffraction technique

      J Ghosh S K Chattopadhyay A K Meikap S K Chatterjee P Chatterjee

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      Present study considers microstructural characterization of vanadium-based palladium (V–Pd) alloys, which are widely used in marine environment due to their high corrosion resistance. The X-ray diffraction line profile analysis (XRDLPA) have been used to assess the microstructure in body centred cubic (bcc) V–Pd alloys having four different nominal compositions in wt.%. X-ray diffraction line broadening analysis on V–Pd alloys has been performed by using different methods like the Warren–Averbach, double-Voigt and Rietveld methods. Finally microstructural defect parameters such as domain size (𝐷), r.m.s. microstrain 〈 𝜀21/2, twin fault (𝛽'), spacing fault (𝛼𝜀) and deformation stacking fault (𝛼) were evaluated in these alloys by Fourier line shape analysis using Rietveld method in which the X-ray diffraction profiles of these alloys were described by the pseudo-Voigt function to fit the experimental data. From analysis it has been observed that twin fault, 𝛽', and the spacing fault, 𝛼𝜀, are totally absent in these bcc alloy systems because the twin fault, 𝛽', has been observed to be either negative or very small (within experimental error limit) for these alloy systems and the spacing fault, 𝛼𝜀, appears to be negative. This analysis also revealed that the deformation stacking fault, 𝛼, is significantly present in this alloy system and increases with Pd content.

    • Study of microstructure in vanadium–palladium alloys by X-ray diffraction technique

      J Ghosh S K Chattopadhyay A K Meikap S K Chatterjee P Chatterjee

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