On amorphization and nanocomposite formation in Al-Ni-Ti system by mechanical alloying

Amorphous structure generated by mechanical alloying (MA) is often used as a precursor for generating nanocomposites through controlled devitrification. The amorphous forming composition range of ternary Al-Ni-Ti system was calculated using the extended Miedema's semi-empirical model. Eleven compositions of this system showing a wide range of negative enthalpy of mixing (-ΔH mix) and amorphization (-ΔH amor) of the constituent elements were selected for synthesis by MA. The Al88Ni6Ti6 alloy with relatively small negative ΔH mix (-0.4 kJ/mol) and ΔHamor (-14.8 kJ/mol) became completely amorphous after 120 h of milling, which is possibly the first report of complete amorphization of an Al-based rare earth element free Al-TM-TM system (TM = transition metal) by MA. The alloys of other compositions selected had much more negative ΔHmix and Hamor; but they yielded either nanocomposites of partial amorphous and crystalline structure or no amorphous phase at all in the as-milled condition, evidencing a high degree of stability of the intermetallic phases under the MA environment. Hence, the negative ΔH mix and ΔH amor are not so reliable for predicting the amorphization in the present system by MA

Radioactive isotopes reveal a non sluggish kinetics of grain boundary diffusion in high entropy alloys

High entropy alloys (HEAs) have emerged as a new class of multicomponent materials, which have potential for high temperature applications. Phase stability and creep deformation, two key selection criteria for high temperature materials, are predominantly influenced by the diffusion of constituent elements along the grain boundaries (GBs). For the first time, GB diffusion of Ni in chemically homogeneous CoCrFeNi and CoCrFeMnNi HEAs is measured by radiotracer analysis using the $^{63}$Ni isotope. Atom probe tomography confirmed the absence of elemental segregation at GBs that allowed reliable estimation of the GB width to be about 0.5 nm. Our GB diffusion measurements prove that a mere increase in number of constituent elements does not lower the diffusion rates in HEAs, but the nature of added constituents plays a more decisive role. The GB energies in both HEAs are estimated at about 0.8-0.9 J/m$^2$, they are found to increase significantly with temperature and the effect is more pronounced for the CoCrFeMnNi alloy.Comment: 11 pages, 9 figure

A localised chlorophyll deficiency associated with male sterility in Nicotiana tabacum L.

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Beneficiation of Indian Heavy Mineral Sands- Some New Possibilities Identified by Tata Steel

Titanium, the 9th most abundant element on the earth's crust, is available mostly (90%)in the form of ilmenite (FeO.TiO2) and leucoxene (weathered ilmenite). These titanium bearing minerals occur either as placer minerals or some times, as rock deposits (e.g. in canada and Norway

Bounds and error control for eigenvalues

Control and estimation of errors are important but difficult aspects of any analysis from which the numerical results are necessarily approximate. The order of difficulty is greater for local or distributed quantities like stresses and displacements than for global Of integrated parameter~ like eigenvalues and stiffnesses. To really bound a desired quantity between a pair of dose upper and lower bounds one should obtain either an oscillatory but clear convergence or, preferably, two rapidly converging sequences one from above and the other from below. Application of the two complementary variational principles of energy and complimentary energy, when both are possible to apply, do yield upper and lower bound approximations. But these or other alternate methods are generally expensive. On the other hand it would be advantageous if one basic procedure could be perturbed in a simple manner to provide both lower and upper bounds and to refine the solution and control the errors without undue effort. This paper discusses this concept and presents three powerful methods to closely bound any desired parameter in a problem. These are particularly valuable for eigenvalue problems

Stock assessment of sciaenid resources of India

B e catches of Sew fishes decrensed froin 1'379 to 1980 and later increased in sages frum 1961 to 1984,1985 to 87 and 1988~089 . Gujantand Mahamshtra togehrwntribured 52%of zdal sdaenid calches along she wcsl coast. hi b.%h the states, the landings during tht: f~stfe w years showed an incmsing trend whercss during the remaining period, the catches and permrage eontnbuticn varied. Along the east coast dso i?r,e sciaenid landings showed annual fluctuations

Cosmogenic records in the recently fallen Devgaon (H4) chondrite

A stony meteorite fell in the village Devgaon, Bastar district, Chattisgarh, Central India on 2001 February 12. The meteorite was fully covered with fusion crust and weighed about 12 kg. Chemical composition, cosmogenic nuclear tracks, radionuclides and noble gases have been studied to determine its classification, the preatmospheric size and the irradiation history

Novel multicomponent B2-ordered aluminides: Compositional design, synthesis, characterization, and thermal stability

For the first time, multicomponent alloys belonging to a B2-ordered single phase were designed and fabricated by melting route. The design concept of high entropy alloys is applied to engineering the transition metal sublattice of binary B2 aluminide. The equiatomic substitution of transition metal elements in the Ni sublattice of binary AlNi followed to produce Al(CoNi), Al(FeNi), Al(CoFe), Al(CoFeNi), Al(CoFeMnNi), and Al(CoCuFeMnNi) multicomponent alloys. CALculation of PHAse Diagrams (CALPHAD) approach was used to predict the phases in these alloys. X-ray diffraction and transmission electron microscopy were used to confirm the B2 ordering in the alloys. Thermal stability of the B2 phase in these alloys was demonstrated by prolonged heat treatments at 1373 K and 1073 K up to 200 h. © 2020 by the author. Licensee MDPI, Basel, Switzerland

Sunstein, Statutes, and the Common Law – Reconciling Markets, the Communal Impulse, and the Mammoth State

Professor Cass Sunstein\u27s new book, After the Rights Revolution: Reconceiving the Regulatory State, builds upon, and in important ways seeks to integrate, much of Professor Sunstein\u27s work over the past several years. He has been one of our most prolific and influential writers on issues of governmental structure, approaching the subject both from more or less conventional administrative law perspectives and from the constitutional perspectives of separation of powers. His work has dealt with a tension often addressed in the literature, that between the eighteenth-century Madisonian constitutional engine of limited, internally checked government and the realities of our sprawling contemporary structures. A particular contribution of Sunstein\u27s has been to insist on bringing forward the Madisonian visions, on their accommodation, not their abandonment. This contribution entails rather vigorous disagreement with the economics-driven theorists of public choice, on the right, and those of deconstructionism, on the left. Sunstein wants to build a conceptual framework for contemporary government that embraces the Madisonian ideal of government structured to serve genuinely public ends in face of the risk of faction; that vision entails both reaching agreement on appropriate distinctions between public and private ends, and finding effective contemporary expression of such ideas as checks and balances

Packages of Practices for Sustainable, Ecofriendly Mariculture (Land-based Saline Aquaculture and Seafarming)

The problems of fast growing human population and protein deficit, particularly in the developing countries continue to exert pressure on the fisheries resources available for exploitation in the wild water bodies. The increasingly limited opportunities in the capture fisheries sector have generated considerable interest in aquaculture