A K Singh
Articles written in Bulletin of Materials Science
Volume 5 Issue 3-4 August 1983 pp 219-230
The various methods of obtaining the kinetics data in pressure-induced transformations have been briefly reviewed. Some of the recent results obtained for the pressure-induced alpha-omega transformation in titanium, and fcc-bcc transformation in ytterbium have been discussed. The general features of the kinetics data have been compared with those for other transformations available in literature.
Volume 6 Issue 2 May 1984 pp 395-403 Phase Transitions
The pressure-volume relation of ytterbium has been determined up to 9 Gpa using tungsten carbide opposed anvil high pressure x-ray camera. The fcc phase of ytterbium is observed between one atmosphere and 4 GPa and the bcc phase above 3·5 GPa. The bcc phase can be metastably retained down to 1 GPa by gradually decreasing the pressure from a region where only bcc phase alone is observed. The bulk modulus,
Volume 6 Issue 6 December 1984 pp 1001-1007
Results of measurement of elastic modulii on As-Sb-Se glasses are reported and their composition dependence discussed. The Young’s and the shear modulii lie in the range of 170–210 and 65–80 kb respectively. These values are typical of chalcogenide glasses. For (As, Sb)40Se60 glasses, the modulii increase monotonically with increasing Sb2Se3 content. The observed composition dependence of the modulii for the As
Volume 8 Issue 1 February 1986 pp 53-60
The results of measurement of thermal expansion coefficient from 50°C to the softening temperature on eight glass compositions of the As-Sb-Se system are presented. Measurements have been made on (As, Sb)40Se60 and As
Volume 9 Issue 1 March 1987 pp 13-19
The results of non-isothermal crystallization studies performed at different heating rates on batches of As2Se3 glasses prepared from melts at 400°C, 600°C and 800°C are reported. The peak temperature of crystallization
Volume 9 Issue 3 August 1987 pp 225-233
The use of energy dispersive method has been discussed to record the X-ray diffraction data from a tungsten carbide opposed anvil high pressure set-up. It is pointed out that a proper collimation of the incident and the diffracted beams can eliminate the scattering from the gasket material. This results in an appreciable improvement in the quality of the recorded diffraction data. The choice of the various parameters has been discussed. The data on sodium chloride are presented in support of this analysis.
Volume 10 Issue 3 May 1988 pp 205-216
Variations in the halfwidth values of X-ray reflections from fatigue-cycled, polycrystalline aluminium samples have been analysed. An oscillatory variation of the halfwidths with fatigue cycling has been observed. Analysis of the diffraction line profiles indicates that broadening arises mainly because of the build-up of microstrains during fatigue cycling. The present data indicate that (i) broadening due to fatigue cycling increases with glancing angle; (ii) changes in halfwidth and integral widths, due to fatigue cycling, are comparable and (iii) (
Volume 12 Issue 3-4 September 1989 pp 245-261 International Conference On Recent Advances In Materials And Processes
The advantages of a new semi-wet method for the synthesis of (Ba, Ca)TiO3 and YBa2Cu3O7 − y powders from precursor carbonates are described. The precursor carbonates are prepared using chemical coprecipitation technique under controlled pH conditions to ensure uniform distribution of Ba+2/Ca+2 and Y+3/Ba+2 ions. It is shown that the powders synthesized by this route possess better chemical homogeneity as compared to those obtained by the conventional ceramic technique involving calcination of a mixture of BaCO3, CaCO3, TiO2 and Y2O3, BaCO3, CuO powders. The behaviour of the ferroelectric (Ba, Ca)TiO3 and the superconducting YBa2Cu3O7 − y ceramics prepared from powders obtained by our method are found to be markedly different from those known for the conventionally prepared ceramics.
Volume 13 Issue 5 December 1990 pp 305-311
Laminated composites consisting of alternate layers of aluminium alloy sheets and unidirectional Kevlar-49 fibre epoxy composites were prepared using two different aluminium alloys DTD 687 and aluminium-lithium alloy. Tensile, compressive and interlaminar shear strengths of the laminates were measured. The residual stresses in the aluminium alloy sheets arising out of thermal mismatch between aluminium alloys and aramid fibres were also measured. It is found that the laminates have lower density, higher tensile strength and marginally lower Young’s modulus as compared with monolithic alloy sheets.
Volume 14 Issue 1 February 1991 pp 65-70
A set-up is described for the measurement of longitudinal and transverse wave velocities in a solid under gas pressures up to 0·4 GPa. To check the performance of the set-up, the elastic constants of Se and As2Se3 glasses and their pressure derivatives were obtained from the wave velocity data and compared with the data available in the literature.
Volume 14 Issue 3 June 1991 pp 767-770 International Conference On Superconductivity—II
Thermoelectric power (TEP) of two YBa2Cu3O7−
Volume 19 Issue 3 June 1996 pp 601-605
The equations have been derived for the trigonal system to calculate the lattice strains produced by the non-hydrostatic pressure condition which arises when the sample is compressed between the anvils without any pressure transmitting medium.
Volume 22 Issue 6 October 1999 pp 975-979 Phase Transitions
Polycrystalline samples of Ba5RTi3Nb7O30 [R=Nd, Eu, Gd], were prepared using high-temperature solid-state reaction technique. Preliminary X-ray structural analysis of the compounds shows the formation of single phase compounds (orthorhombic crystal system) at room temperature. Detailed studies of dielectric properties (
Volume 42 | Issue 6
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