Evolution of the Microstructure of a CuCr1Zr Alloy during Direct Heating by Electric Current

Round tensile test specimens of an age-hardened CuCr1Zr alloy were subjected to direct electrical current heating in a Gleeble thermal–mechanical simulator at 800 °C. The mechanical properties were monitored by the Vickers hardness test, and the changes in the grain structure were examined by light metallography. A quantitative analysis of the size and distribution of fine precipitates during annealing was carried out using transmission electron microscopy (TEM). The grain structure showed a gradient corresponding to the gradient of the temperature on the test piece. Annealing for 60 s at 800 °C resulted in a partially (~50%) recrystallized structure with new grains about 45 μm in diameter. In the as-delivered condition, TEM documented tiny (1 to 4 nm) coherent chromium precipitates inducing strain fields in the matrix. During overaging, the particles lost their coherence and gradually coarsened up to a mean diameter of 40 nm after 300 s at 800 °C. The coarsening kinetics obeys Lifshitz, Sloyzov, and Wagner’s theory.

Stigma and fear during COVID-19: essentializing religion in an Indian context

A cursory inquest into the effects of SARS-CoV-2 exposes how easily the ramification of the pandemic has moved over from the physio-social to the psychosocial state of humans all over the world. Derogatory nomenclatures such as ‘Chinese-virus’ or ‘Corona-jihad’ can be seen as a part of a disjunctive politics of ‘representation’ as opposed to ‘representing’ with a metonymic effect. Such politics violates the protocol on naming new human infectious diseases set by World Health Organization. It also insinuates a long-term socio-political impression on the mental state of an individual or a social group, which may have an emasculating effect on the global solidarity to fight the virus. This calls for a nuanced psychosocial investigation with a specific analysis of how the ensuing stigmatization and fear can aggravate the contagion. With specific reference to the Indian sub-continent, this paper explains the socio-political orientation behind the essentialisation of a religious group that has led to the indictment of the minority community. By using Wagner’s theory of essentialisation and Critical Race Theory, this article shall endeavor to explore how media may play a crucial role in stigmatizing communities. Secondly, the paper also argues that the spiraling effect of such ostracisation leads to stigma and fear within the group which is not only dehumanizing but also detrimental to the concerted effort to contain the pandemic.

Public Expenditure and Economic Growth: A Test of Wagner’s and Keynes Hypotheses in Nigeria and Angola Economies

This study verifies the validation of Wagner’s theory and Keynes's hypothesis between three main government expenditure components (Health expenditure, education expenditure, and capital investment expenditure) and economic growth in Nigeria and Angola. The study employs Johansen cointegration and pairwise granger causality as the estimation techniques. Findings revealed no evidence of long-run relationships with government expenditure components of health, education, and capital investment and economic growth. The study equally reveals the validation of Wagner’s theory between growth and expenditure on health in both Nigeria and Angola. Evidence that confirms both Wagner’s theory and Keynes's hypothesis between growth and expenditure on education in Angola and validation of only Keynes hypothesis in Nigeria was found. Also, the study confirms the validation of Keynes's hypothesis between government expenditure on capital investment in both Nigeria and Angola

Non-Isothermal Oxidation Behaviors and Mechanisms of Ti-Al Intermetallic Compounds

Non-isothermal oxidation is one of the important issues for the safe application of Ti-Al alloys, so this study aimed to illustrate the non-isothermal oxidation behaviors and the corresponding mechanisms of a TiAl-based alloy in comparison with a Ti3Al-based alloy. The non-isothermal oxidation behaviors of Ti-46Al-2Cr-5Nb and Ti-24Al-15Nb-1.5Mo alloys in pure oxygen were comparatively investigated with a thermogravimetry-differential scanning calorimetry (TGA/DSC) simultaneous thermal analyzer heating from room temperature to 1450 °C with a heating rate of 40 °C/min. When the temperature rose above 1280 °C, the oxidation rate of the Ti-46Al-2Cr-5Nb alloy sharply increased and exceeded that of the Ti-24Al-15Nb-1.5Mo alloy owing to the occurrence of internal oxidation. When the temperature was higher than 1350 °C, the oxidation rate of the Ti-46Al-2Cr-5Nb alloy decreased obviously due to the generation of an oxygen-barrier β-Al2TiO5-rich layer by a chemical reaction between Al2O3 and TiO2 in the oxide scale. Based on Wagner’s theory of internal oxidation, the reason for the occurrence of internal oxidation in the Ti-46Al-2Cr-5Nb alloy is the formation of the α phase in the subsurface, while no internal oxidation occurred in the Ti-24Al-15Nb-1.5Mo alloy due to the existence of the β phase in the subsurface with the enrichment of Nb and Mo.

Thermodynamic Modeling of the Processes of Interaction of Calcium, Magnesium, Aluminum and Boron with Oxygen in Metallic Melts

A method for calculation of the diagrams of steel deoxidation and modification by calcium, magnesium, aluminum and boron was developed. The coordinates of the liquidus surfaces of the oxide systems B2O3–Al2O3–MgO, B2O3–Al2O3–CaO, B2O3–MgO–CaO were found at 1873 K. The energy parameters were determined for the theory of subregular ionic solutions of the studied oxide systems. The coordinates of the solubility surfaces for the systems Fe–Mg–Al–B–O, Fe–Ca–Al–B–O, Fe–Mg–Ca–Al–B–O were calculated. The effect of the total pressure on solubility of magnesium and calcium in liquid iron was studied. The activity of the components of the metallic melt was calculated using the first-order interaction parameters (Wagner's theory). The activities of the components of solid solutions (oxides and spinels) were equated with their molar fractions. It was shown that during extensive refining of metal from the oxygen, only a small fraction of boron oxidizes and these oxides form fraction of the oxide melts. The major non-metallic oxide inclusions were magnesia spinel, calcium bialuminate and liquid oxide formations. The "free" boron was dissolved in liquid metal in amounts which were in equilibrium with oxide phases.

Proposal of a Simple Evaluation Method for Sloshing Impact Pressure on Flat Roofs

Sloshing is one of important issues for both loop-type and tank-type fast reactors with free liquid surface. Periods of seismic vibration are lengthened by base isolation systems installed to prevent damages to facilities during earthquakes, and get close to the natural periods of sloshing. As a result, sloshing is promoted. Sloshing waves are assumed to even reach a roof slab of a reactor vessel in severe seismic conditions. It is important to evaluate structural integrity for sloshing impacts on roofs. However, there are not any established evaluation methods for impact pressure on flat roofs yet. Therefore, in this study, a simple evaluation method is proposed based on Wagner’s theory. The effectiveness of the proposed method is illustrated using computational fluid dynamics analysis and literature data of sloshing experiments.

Defect Structure of the NiS2 Disulphide

Defect structure of NiS2 disulphide has been studied using marker technique and sulphidation rate measurements of NiS to NiS2, as a function of temperature and sulphur vapor pressure. It has been found that cation sublattice of the discussed compound is predominantly disordered and the prevailing defects are doubly ionized interstitial cations and quasi-free electrons. Using kinetic results, the self-diffusion coefficient of cations in NiS2 has been calculated basing on Wagner's theory of metal oxidation.