Orientation-Dependent Developments in Misorientation and Residual Stress in Rolled Aluminum: The Defining Role of Dislocation Interactions

Orientation-dependent developments in misorientation and residual stress, in rolled aluminum, were quantified experimentally and simulated numerically. The latter involved analysis using a crystal plasticity finite element model, accounting for anisotropies in slip system hardening but neglecting near-neighbor interactions, and discrete dislocation dynamics of the single crystals. Both were successful in capturing the experimental patterns of orientation dependence. Numerical simulations, without slip transfer across the neighboring grains, thus established the defining role of dislocation interactions in establishing orientation-sensitive microstructural evolution.     

Direct Experimental Observations on Concurrent Microstructure and Magnetic Property Developments in Non-Grain Oriented Electrical Steel

Non-grain oriented electrical steel, with minor in-grain orientation gradients, was subjected to interrupted tensile deformations and concurrent microtexture, magnetic property and residual stress measurements. After the upper yield point, clear signatures of mechanical stress relief were observed. Changes in orientation gradients led to annihilation of low-angle (1 to 3 deg) boundaries. Prior deformation compressive residual stresses became tensile and magnetic properties improved. Beyond an optimum true strain of 0.01, this boundary annihilation ceased, compressive stresses were generated, and magnetic properties degraded.     

A Novel RFET Sensor for Label-Free Biomolecule Detection

Silicon - In the current scenario, COVID-19 has created a havoc negative impact on the lives of the people, which have triggered the research interest on the design and development of sensitive,...     

Relating microtexture and dynamic micro hardness in an extruded AA8090 alloy and AA8090-8 vol% SiCp composite

The present study involves combined measurements of microtexture and dynamic ultra micro hardness (DUH) in hot extruded AA8090 aluminum alloy and its composite reinforced with 8 vol% SiC_p. Both the materials show strong crystallographic fiber textures—111 and 001. The dynamic micro hardness shows a clear pattern of difference between these two fiber textures, 111 oriented grains being harder and stiffer. The difference in θ/d between the fibers, where θ and d are the average cell misorientation and cell size, respectively, was marginal in the alloy and thus cannot explain the observed hardness difference. The hardness difference can be explained from the difference in Taylor factors between the respective fibers. Elastic stiffness values estimated from microtexture and DUH follow a similar trend qualitatively.     

Role of grain/phase boundary nature on the formation of hydrides in Zr-2.5%Nb alloy

Hydride formation in a fully recrystallized Zr-2.5%Nb alloy having equiaxed grains of α and β was studied. Primarily the electron back scatter diffraction (EBSD) technique was used for the characterization of the hydrides in conjunction with optical and transmission electron microscopy. Hydrides were found to have preferentially formed along the α/β interfaces. Microtexture measurements showed that the orientation relationship (OR) between α and δ-hydride phase was (0 0 0 1)_α || (1 1 1)_δ and || [1 1 0]_δ. It was shown that the hydrides have higher preference to form along such α/β interfaces which have one of the low index planes of the β phase constituting the interface.     

Strain Mode Dependence of Deformation Texture Developments: Microstructural Origin

Fully recrystallized commercial-purity aluminum sheets were deformed by limiting dome height tests, the following strain modes: uniaxial tension (US), near plane strain tension (PS), and equibiaxial tension (BS) were identified using standard procedure. The deformation texture developments differed significantly depending on the strain mode. Although the full constraints Taylor (FCT) model captured the texture developments in US, it failed to reproduce deformation textures in PS and especially in BS. The Advanced LAMEL (ALAMEL) model and the crystal plasticity finite element method (CPFEM) were, however, successful with respect to all three strain modes. Microtexture data brought out interesting observations of orientation gradients. First, the orientation gradients increased from US to PS to BS. Second, such gradients were mostly around initial (or prior deformation) grain boundary regions. A simple algorithm, and an associated computer program, was developed to demarcate such near boundary gradient zones (NBGZs). The area fraction and severity of NBGZ seemed to affect the texture development; FCT was reasonably successful at low NBGZ, whereas high NBGZ required the ALAMEL and the CPFEM models that are capable of addressing strain heterogeneity and grain interactions.     

In support and extension of the mechanism of densification,strengthening and deformation behaviour of YBa2Cu3O7−x -Ag2O superconducting composites prepared by the powder metallurgy route

In the evolution of potential shape-forming processes for high-temperature superconducting ceramics, the powder metallurgy route, using YBa₂Cu₃O_7–x and Ag₂O powders to fabricate flexible superconducting composite wires by extrusion, occupies a unique status. The processing route is novel, particularly with respect to the strength and deformability of the product at various stages. The extruded wires display a sharp resistive transition upon oxygen annealing. A phenomenological model of the mechanism explaining the microstructural behaviour of this composite had been proposed earlier by the authors. In this communication a processing-microstructure-property correlative approach has been adopted with a view to establishing experimental support for, as well as to effect an extension of, the mechanism of strengthening, densification and deformation behaviour of YBa₂Cu₃O_7–x-Ag₂O superconducting composites prepared by the powder metallurgy route. The results of mechanical testing and microscopic investigation are used in conjunction to complete the understanding of the mechanism.