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Assuming plane strain conditions and taking phase transformations into account, finite element analysis was carried out using a bead-by-bead deposition model as well as two different lumped models. The effects of post-weld heat treatment at 600 °C were also studied. Predicted residual stresses were verified using X-ray diffraction method. While both bead-by-bead and lumped models were found to overestimate the maximum residual stress in as-welded condition, the latter facilitated a safer upper-bound estimate of the residual stress. The net tensile stress in the weld metal was found to decrease as a result of solid-state transformation of austenite to ferrite. Further, a significant part of stress relief was found to occur in the first half hour of the holding time during post-weld heat treatment. A formula was developed for estimating the maximum residual stress in post-weld heat treated condition. [ABSTRACT FROM AUTHOR]

Abstract: Arsenic sulfide and arsenic selenide glasses, batched from elemental precursors in stoichiometric proportions, are synthesised in ≤35min via microwave heating in a domestic microwave oven (DMO). The DMO products are compared with the stoichiometric glasses made by conventional resistive furnace melting using: X-ray diffraction (XRD); transmission electron microscopy with selected area electron diffraction (TEM-SAED); analytical scanning electron microscopy; optical microscopy; differential thermal analysis (DTA); and Fourier transform infrared spectroscopy. From XRD and TEM-SAED, only part of the DMO As–S product is amorphous and exhibits up to three DTA glass transitions (T gs) showing that homogenisation has not taken place. In contrast, As40Se60 glass is readily prepared in the DMO and has similar properties to conventionally melted As40Se60 glass. Furthermore, the DMO As40Se60 glass can be patterned using hot embossing and drawn to fibre. [Copyright &y& Elsevier]

Ferroelectric Sr1−xBaxBi2(Nb0.5Ta0.5)2O9 and Sr0.5Ba0.5Bi2(Nb1−yTay)2O9 were synthesized by solid state reaction route. X-ray diffraction studies confirm the formation of single phase layered perovskite solid solutions over a wide range of compositions (x=y=0.0, 0.25, 0.50, 0.75 and 1). The lattice parameters and the Curie temperature (Tc) have been found to have linear dependence on x and y. Transmission electron microscopy (TEM) suggest the lowering of orthorhombic distortion with increasing Ba2+ substitution. Variations in microstructural features as a function of x and y were monitored by scanning electron microscopy (SEM). The dielectric constant at room temperature increases with increase in both x and y. Interestingly Ba2+ substitution on Sr2+ site induces diffused phase transition and diffuseness increases with increasing Ba2+ concentration. [Copyright &y& Elsevier]

In the present study, lead-free piezoelectric (1-x)[(Bi 0.96 La 0.04 ) 0.5 Na 0.5 TiO 3 ]-(x)[Ba 0.90 Ca 0.10 TiO 3 ] ceramics with x ≤ 0.20 have been prepared at optimum temperature (950°C–1050 °C) by employing semi-wet technique. The effect of Ba 0.90 Ca 0.10 TiO 3 (BCT) content on the phase formation, surface morphology, dielectric and piezoelectric properties is systematically investigated and characterized by X-ray diffraction (XRD), Raman Spectroscopy, Field emission Scanning electron micrographs (FE-SEM), Impedance analyzer. XRD analysis shows phase transformation from rhombhohedral to tetragonal with the addition of BCT and the average grain size decreases with BCT content, x. Temperature dependent dielectric behavior exhibits two phase transitions, i.e. depolarization temperature; T d and phase transition temperature; T m . The phase transitions; T m tends to diffuse with increasing x and exhibited a broad frequency dependent maximum upto x ≤ 12. Optimum piezoelectric and dielectric properties (i.e., d 33 = 165 pC/N, k p = 39%, k t = 47% and k 33 = 57%, ε r = 1585, tan δ = 0.07) in the studied system have been obtained. [ABSTRACT FROM AUTHOR]