Investigation of early stage deformation mechanisms in a metastable β titanium alloy showing combined twinning-induced plasticity and transformation-induced plasticity effects

International audienceAs expected from the alloy design procedure, combined Twinning Induced Plasticity (TWIP) and Transformation Induced Plasticity (TRIP) effects are activated in a metastable β Ti-12(wt.%)Mo alloy. In-situ Synchrotron X-ray diffraction (XRD), electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) observations were carried out to investigate the deformation mechanisms and microstructure evolution sequence. In the early deformation stage, primary strain/stress induced phase transformations (β->ω and β->α'') and primary mechanical twinning ({332} and {112}) are simultaneously activated. Secondary martensitic phase transformation and secondary mechanical twinning are then triggered in the twinned β zones. The {332} twinning and the subsequence secondary mechanisms dominate the early stage deformation process. The evolution of the deformation microstructure results in a high strain hardening rate (~2GPa) bringing about high tensile strength (~1GPa) and large uniform elongation (> 0.38)

Combination of electron energy-loss spectroscopy and energy dispersive x-ray spectroscopy to determine indium concentration in InGaN thin film structures

We demonstrate a method to determine the indium concentration, x, of In x Ga1-x N thin films by combining plasmon excitation studies in electron energy-loss spectroscopy (EELS) with a novel way of quantification of the intensity of x-ray lines in energy-dispersive x-ray spectroscopy (EDXS). The plasmon peak in EELS of InGaN is relatively broad. We fitted a Lorentz function to the main plasmon peak to suppress noise and the influence from the neighboring Ga 3d transition in the spectrum, which improves the precision in the evaluation of the plasmon peak position. As the indium concentration of InGaN is difficult to control during high temperature growth due to partial In desorption, the nominal indium concentrations provided by the growers were not considered reliable. The indium concentration obtained from EDXS quantification using Oxford Instrument ISIS 300 x-ray standard quantification software often did not agree with the nominal indium concentration, and quantification using K and L lines was inconsistent. We therefore developed a self-consistent iterative procedure to determine the In content from thickness-dependent k-factors, as described in recent work submitted to Journal of Microscopy. When the plasmon peak position is plotted versus the indium concentration from EDXS we obtain a linear relationship over the whole compositional range, and the standard error from linear least-squares fitting shows that the indium concentration can be determined from the plasmon peak position to within Δx = ± 0.037 standard deviation

Developing the next generation of renewable energy technologies: an overview of low-TRL EU-funded research projects

A cluster of eleven research and innovation projects, funded under the same call of the EU’s H2020 programme, are developing breakthrough and game-changing renewable energy technologies that will form the backbone of the energy system by 2030 and 2050 are, at present, at an early stage of development. These projects have joined forces at a collaborative workshop, entitled ‘ Low-TRL Renewable Energy Technologies’, at the 10th Sustainable Places Conference (SP2022), to share their insights, present their projects’ progress and achievements to date, and expose their approach for exploitation and market uptake of their solutions

“It’s Like Hating Puppies!” Employee Disengagement and Corporate Social Responsibility

Corporate social responsibility (CSR) has been linked with numerous organizational advantages, including recruitment, retention, productivity, and morale, which relate specifically to employees. However, despite specific benefits of CSR relating to employees and their importance as a stakeholder group, it is noteworthy that a lack of attention has been paid to the individual level of analysis with CSR primarily being studied at the organizational level. Both research and practice of CSR have largely treated the individual organization as a “black box,” failing to account for individual differences amongst employees and the resulting variations in antecedents to CSR engagement or disengagement. This is further exacerbated by the tendency in stakeholder theory to homogenize priorities within a single stakeholder group. In response, utilizing case study data drawn from three multinational tourism and hospitality organizations, combined with extensive interview data collected from CSR leaders, industry professionals, engaged, and disengaged employees, this exploratory research produces a finer-grained understanding of employees as a stakeholder group, identifying a number of opportunities and barriers for individual employee engagement in CSR interventions. This research proposes that employees are situated along a spectrum of engagement from actively engaged to actively disengaged. While there are some common drivers of engagement across the entire spectrum of employees, differences also exist depending on the degree to which employees, rather than senior management, support corporate responsibility within their organizations. Key antecedents to CSR engagement that vary depending on employees’ existing level of broader engagement include organizational culture, CSR intervention design, employee CSR perceptions, and the observed benefits of participation

Attribute-Based Refinement of Software Architectures

This paper aims to show the usefulness of attaching attributes to pieces of software architectures, in order to direct a transformation and refinement process. These attributes are properties that can be considered as abstract ways to express architectural structures, and characteristics that constrain the refinement process. Then we define a methodology that consists in refining and transforming an architecture on the basis of the attributes attached to it. The methodology will be illustrated on a case study

Attribute-Based Refinement of Software Architectures

This paper aims to show the usefulness of attaching attributes to pieces of software architectures, in order to direct a transformation and refinement process. These attributes ways to express architectural structures, and characteristics that constrain the refinement process. Then we define a methodology that consists in refining and transforming an architecture on the basis of the attributes attached to it. The methodology will be illustrated on a case study. 1. Introduction an

Ultrafine grain recrystallisation of a metastable-β Ti-alloy via conventional thermomechanical processing

Alloys with ultrafine grains (UFG) offer high strength potentially combined with ductility. Until now, producing ultrafine grains in ingot alloys has required either severe plastic deformation techniques or flash annealing, neither of which are scalable to bulk alloy production. In this work, we formed submicronic grains in the metastable β titanium alloy Ti-20Nb-6Zr (at%), using conventional cold rolling and annealing at 823K in a conventional furnace. The cold rolling (298K) transformed the β structure mostly to α” martensite, but if the rolling temperature was raised to 453K, martensite formation was supressed, and no grain refinement occurred during the subsequent similar annealing treatment. Therefore, we attribute the formation of ultrafine grains to a mechanism involving stress-induced martensite and its reverse transformation

Ultrafine grain recrystallisation of a metastable-β Ti-alloy via conventional thermomechanical processing

Alloys with ultrafine grains (UFG) offer high strength potentially combined with ductility. Until now, producing ultrafine grains in ingot alloys has required either severe plastic deformation techniques or flash annealing, neither of which are scalable to bulk alloy production. In this work, we formed submicronic grains in the metastable β titanium alloy Ti-20Nb-6Zr (at%), using conventional cold rolling and annealing at 823K in a conventional furnace. The cold rolling (298K) transformed the β structure mostly to α” martensite, but if the rolling temperature was raised to 453K, martensite formation was supressed, and no grain refinement occurred during the subsequent similar annealing treatment. Therefore, we attribute the formation of ultrafine grains to a mechanism involving stress-induced martensite and its reverse transformation

A distributed adaptive block matching algorithm: Dis-ABMA

In the context of motion estimation for video sequences processing, variable block size algorithms, like the Adaptive Block Matching Algorithm (ABMA), have been proposed to match better "objects in motion" compared to the classical BMA. However, the variable block size grid derivation and the related motion estimation relies on a regularization process which implies heavy iterative and inter-dependent computations. Though the parallelization of the BMA is straightforward, the ABMA needs a deeper analysis before its implementation in a distributed environment: this is the goal of this paper. We first designed a modelization of the motion estimation of ABMA. This model call lead to several different distributed versions. A specific distributed model, with one master and several slaves, is then described. An implementation of this model has been realized and experimentations demonstrate a linear speedup with respect to the number of processors. (C) 2001 Elsevier Science B.V. All rights reserved