This research article investigates the effect of SiO2 flux on Nd:YAG laser welding of 5 mm thick plates of super-austenitic stainless steel, AISI 904L. Microstructure studies revealed multidirectional grain growth comprising columnar and cellular dendrites along with a prominent, fine equiaxed dendritic growth at the centerline of the fusion zone. Tensile studies showcased the fracture at the fusion zone in all the trials. The average tensile strength reported for the flux assisted laser weldments was found to be 587 MPa which was slightly lower than the parent metal. The impoverishment of tensile strength could be attributed to the formation of centerline equiaxed grains. Similarly the impact toughness of the joints was found to be 58 J. The studies demonstrated the possibility of using a 2 kW Nd:YAG laser welding machine to weld 5 mm thick plate with the use of SiO2 flux. A detailed study on the structure–property relationship of flux assisted Nd:YAG laser weldment was carried out using the combined techniques optical microscopy, scanning electron microscopy, and energy dispersive x-ray analysis.

Thermoelectric converters based on silicon nanostructures offer exciting opportunities for higher efficiency, lower cost, ease of manufacturing, and integration into circuits. This paper considers phonon transport in a broad range of nanostructured materials made from Si, Ge, and their alloys. Our model based on the phonon Boltzmann transport equation captures the lattice thermal transport in silicon–germanium (SiGe) nanostructures, including thin films, superlattices (SLs), and nanocomposites. In nanocomposites, the model captures the grain structure using a Voronoi tessellation to mimic the grains and their size distribution. Our results show thermal conductivity in SiGe nanostructures below their bulk counterparts and reaching almost to the amorphous limit of thermal conductivity. We also demonstrate that thermal transport in SiGe nanostructures is tuneable by sample size (thin films), period thickness (SLs), and grain size (nanocomposites) through boundary scattering. Our results are relevant to the design of nanostructured SiGe alloys for thermoelectric applications.

Aluminum matrix composite with 10 wt% of MoO3 particulate reinforcement was synthesized through powder metallurgy technique. The cold upsetting studies of the composites were investigated based on Taguchi L9 orthogonal array experimental design to evaluate the significance of compaction pressure, sintering temperature, and sintering time on strength coefficient. The combination of 350 MPa pressure, 600 °C temperature, and 90 minutes sintering time was identified as the optimum blend for maximum strength coefficient using the main effect plot. From the analysis of variance, compaction pressure and sintering temperature were identified as highly contributing parameters on strength coefficient. Further, a confirmation test was also conducted with the optimum parameter for validation of the Taguchi results. X-ray diffraction and scanning electron microscopy were used to confirm the presence of MoO3 and its uniform distribution over the aluminum matrix.

Indentation deformation of glass under a sharp diamond indenter causes cracking during and after a loading–unloading cycle. To get a deeper insight into the indentation cracking in glass, it is critical to understand the elastic and inelastic deformation behavior of glass under the indenter. In this study, in situ observations during Vickers indentations are carried out for silica, soda-lime, and lead–silicate glasses. It is found that the true contact area during indentation is different from the area estimated from the contact depth and the indenter geometry, and that the ridges of a Vickers indenter affect the contact shape during indentation. The contact region of silicate glasses under a Vickers indenter is not a regular square but a concave square. This results in edge cracking during indentation. It is concluded that the contact shape and the deformation mechanism of glass under the indenter are closely related to its cracking behaviors.

Dual-stage, constant loading-rate followed by constant-load, pyramidal indentation experiments were performed to investigate the strain-rate (10−5–10−1/s) and temperature (295–573 K) dependence of pure magnesium. The estimated total activation energy, Q (0.69–1.01 eV), and apparent activation volume, V* (17–28b3), indicate that plastic deformation is controlled by a dislocation cross-slip mechanism. The results from this work and previous studies confirm that, during pyramidal indentation of Mg, the operative deformation mechanism remains the same over a very wide strain-rate and temperature range.

Hybrid organic–inorganic perovskites (e.g., CH3NH3PbX3, X represents a halide) have been highlighted for various applications, especially as light absorbers in third-generation photovoltaics. In the pursuit of low-cost and efficient perovskite solar technology, it is crucial to develop a facile method to fabricate conformal, compact perovskite films in an inexpensive and reproducible manner. Here, we report high-quality perovskite films controllably deposited via a facile low-temperature (<150°C) vapor-assisted solution process (VASP). Key steps include deposition of the inorganic framework by solution first, followed by a subsequent in situ reaction between the inorganic species and the desired organic vapor. The VASP approach differs from other conventional solution processing techniques because it retards nucleation and enables vigorous reorganization for film growth, with an absence of solvation, hydration, and undesirable structural transitions. Facilitated by excellent film quality, perovskite materials enable a power-conversion efficiency of ∼16.8% in the planar configuration of a solar cell. This method provides a simple approach to perovskite film preparation and paves the way toward high reproducibility and mass production of high-quality absorber films for solar devices.