Thermal stability and grain growth behavior of mechanically alloyed nanocrystalline Fe-Cu alloys

X-ray diffraction, transmission electron microscopy, and differential scanning calorimetry were used to study the thermal stability of highly supersaturated nanocrystalline FexCu100−x alloys (10~80. For 60<=x<=80 fcc and bcc phases coexist. Heating to elevated temperatures leads to structural relaxation, phase separation, and grain growth of the metastable nanocrystalline solid solutions. Single-phase fcc and bcc alloys undergo significant strain release but no appreciable grain growth prior to phase separation. After phase separation pronounced grain growth sets in. In contrast, samples in the two-phase region show some grain growth and significant chemical redistribution even at low temperatures. The phase separation of single-phase fcc and bcc alloys proceeds via different mechanisms: fcc solid solutions decompose by forming small Fe precipitates, while demixing in bcc alloys starts by segregation of Cu atoms to bcc grain boundaries before nucleation of Cu precipitates. These results show that the stability and grain growth behavior of nanocrystalline alloys is strongly affected by the microstructure of the material

Observations of shallow convective clouds generated by solar heating of dark smoke plumes

The SEVIRI instrument on the Meteosat Second Generation satellite with both fine spatial and temporal resolution allows to detect and follow the dynamics of fast developing meteorological events like spreading smoke plumes and the lifecycles of convective clouds. Smoke plumes have the ability to change the atmospheric heat content due to absorption and reduced reflection of solar radiation. By these means they can trigger formation of shallow convective clouds at their edge. A heavy smoke plume emerging from burning Lebanese oil tanks and spreading over adjacent deserts on 17 July 2006 has been observed as an example of such an effect. This study suggests a physical explanation of the observed convection along the edge of the smoke plume, namely the strong thermal contrast resulting from solar heating of the smoke layer

Land Subsidence and Ground-Water Pumping: Outline

10 pages. Contains research sources

Land Subsidence and Ground-Water Pumping: Outline

10 pages. Contains research sources

Gibbs free energy difference between the undercooled liquid and the beta-phase of a Ti-Cr alloy

The heat of fusion and the specific heats of the solid and liquid have been experimentally determined for a Ti60Cr40 alloy. The data are used to evaluate the Gibbs free energy difference, DELTA-G, between the liquid and the beta-phase as a function of temperature to verify a reported spontaneous vitrification (SV) of the beta-phase in Ti-Cr alloys. The results show that SV of an undistorted beta-phase in the Ti60Cr40 alloy at 873 K is not feasible because DELTA-G is positive at the temperature. However, DELTA-G may become negative with additional excess free energy to the beta-phase in the form of defects

Gibbs free-energy difference between the glass and crystalline phases of a Ni-Zr alloy

The heats of eutectic melting and devitrification, and the specific heats of the crystalline, glass, and liquid phases have been measured for a Ni24Zr76 alloy. The data are used to calculate the Gibbs free-energy difference, DeltaGAC, between the real glass and the crystal on an assumption that the liquid-glass transition is second order. The result shows that DeltaGAC continuously increases as the temperature decreases in contrast to the ideal glass case where DeltaGAC is assumed to be independent of temperature

Mechanically driven alloying and grain size changes in nanocrystalline Fe-Cu powders

Highly supersaturated nanocrystalline FexCu100-x alloys (10 less-than-or-equal-to x less-than-or-equal-to 95) have been prepared by mechanical alloying of elemental crystalline powders. The development of the microstructure is investigated by x-ray diffraction, differential scanning calorimetry, and transmission electron microscopy. The results are compared with data for ball-milled elemental Fe and Cu powders, samples prepared by inert gas condensation, and sputtered films. The deformation during milling reduces the grain size of the alloys to 6-20 nm. The final grain size of the powders depends on the composition of the material. Single-phase fcc alloys with x less-than-or-equal-to 60 and single-phase bcc alloys with x greater-than-or-equal-to 80 are formed even though the Fe-Cu system exhibits vanishingly small solid solubilities under equilibrium conditions. For 60 less-than-or-equal-to x less-than-or-equal-to 80, fcc and bcc solid solutions coexist. The alloy formation is discussed with respect to the thermodynamic conditions of the material. The role of the large volume fraction of grain boundaries between the nanometer-sized crystals, as well as the influence of internal strains and stored enthalpies introduced by ball milling, is critically assessed

A Roundtable Conversation: Feminist Collaborative Ethos in International Law

This roundtable discussion focuses on the collective commitment and the praxis of a feminist collaborative ethos in international law to imagine and centre alternative futures in the field. This discussion took place as part of the virtual workshop ‘International Law Dis/Oriented: Queer Legacies, and Queer Futures Workshop’ from which this special issue emerged. In this transcript of the roundtable, Shaimaa Abdelkarim, Farnush Ghadery, and Rohini Sen discuss with Lena Holzer how turning to feminist collectivity – focused on care, collaboration, and solidarity – can help to disrupt and push against gendered, racialised, and colonial power structures embedded in academic spaces. They examine their intertwined positionalities along with various pedagogical and methodological approaches to determine the functions of critical feminist and queer thoughts in international law. Inculcating a praxis of feminist collaborative ethos in the scholarship and teaching of international law, they hope to present a challenge to the artificial individualisation of the profession and its increasing neoliberalisation

Labor Market Trends and Outcomes: What Has Changed since the Great Recession?

We describe trends in wages and labor force participation for the “working class”—whom we define as workers with high school or less education—compared to those with college or more. We compare cyclical peaks over the entire period 1979–2019, with particular focus on the Great Recession (2007–2010) and recovery (2010–2019). We also present results by gender and race. We find real wage growth in the latter period for all workers, but not enough to change the long-term trends of growing inequality and stagnant wages for the less-educated; and we also find that labor force participation continued to decline for the less-educated, even during the recovery. Gaps between whites and blacks also grew, while Hispanics and Asians made more progress. We consider various explanations of these findings and show that the early effects of the 2020‒2021 pandemic recession hurt less-educated workers and those of color more than anyone else