Studies in the organonitrogen chemistry of tin and neighbouring elements

This thesis describes the preparation and properties of some new organonitrogen derivatives of silicon, germanium, and tin. The structural implications of their I.R., (^1)H-NMR. , and mass spectra are discussed with X-ray crystal structures in some cases. A survey of species containing tin-nitrogen bonds, and a discussion of the stereochemistry of tin are also presented. New methyleneamine derivatives of the type (R(_2)CN)(_n)Sn(^IV)C1(_4-n)(n = 2-4), (Ph(_2)CN)(_2)GeC1(_2), [(R(_2)CN)(_2)Sn(^11)](_n),(Ph(_2) CNSn(^11)c1)(_2), and Li(^t)Bu(_2)CN)(_3)Sn(^11) were prepared from the metal chlorides and N-lithioketimines. The adducts Ph(_2)CNH.Sn(^11)Cl(_2), ((^t)Bu(_2)CNH)(_n)Sn(^IV)Cl(_4) (n = 1,2), Ph(_2)CNH. (Ph(_2)CNSn(^11)Cl)(_2). C(_7)H(_8), and (^t)Bu(_2)CNH. (^t)Bu(_2)CNSn(^11)(_2)C1(_3) are described. Attempts to prepare (^t)Bu(_2)CNSn(^IV) led to (^t)BuCN and Sn(^11)Cl(_2). Similar decomposition of ((^t)Bu(_2)CN)(_n)Sn(^IV)c1(_4-n) (n = 2,3) 2,3) led to the imino-tin(II) complexes (^t)Bu(_2)CNH. (^t)Bu(_2)CNSn(_2)(^11)Cl(_3) and (^t)Bu(_2)CNH(_2)(^+). ((^t)Bu(_2)Sn(_3)(^11)C1(_5)(^-). The new M(^IV) derivatives are monomeric, except for the iminotin chlorides [(ph(_2)CN)(_n)Sn(^IV)C1(_4-n)](_m)(n = 2,3; m ≥ 2). The Sn(^11) derivatives are mostly di- or oligomeric, containing three-coordinate tin. Association appears to involve bridging methyleneamino groups. The adducts R(_2)CNH. (R(_2)CN)(_n)Sn(_2)(^11)C1(_4-n) to contain one three-coordinate and one four- coordinate tin atom. The C=N-M skeletons of those compounds containing terminal methyleneamino groups are probably bent with little or no N→M (p→d) π-bonding

Atomic scale investigation of Cr precipitation in copper

The early stage of the chromium precipitation in copper was analyzed at the atomic scale by Atom Probe Tomography (APT). Quantitative data about the precipitate size, 3D shape, density, composition and volume fraction were obtained in a Cu-1Cr-0.1Zr (wt.%) commercial alloy aged at 713K. Surprisingly, nanoscaled precipitates exhibit various shapes (spherical, plates and ellipsoid) and contain a large amount of Cu (up to 50%), in contradiction with the equilibrium Cu-Cr phase diagram. APT data also show that some impurities (Fe) may segregate along Cu/Cr interfaces. The concomitant evolution of the precipitate shape and composition as a function of the aging time is discussed. A special emphasis is given on the competition between interfacial and elastic energy and on the role of Fe segregation

Simulation of Cu Precipitation in Fe-Cu Dilute Alloys with Cluster Mobility

Cu-rich precipitates formation is associated with the precipitation hardening of Fe-Cu based steels and the embrittlement of reactor pressure vessel steels under neutron irradiation. The accurate modeling of the time evolution of Cu-rich precipitates is therefore of fundamental importance for the design of Fe-Cu based steels and the prediction of the irradiation induced shift of the ductile to brittle transition temperature of reactor pressure vessels. This work applies cluster dynamics with mobile Cu monomers and clusters to model Cu precipitation in dilute Fe-Cu alloys at several temperatures. Optimized model parameters can be used to simulate the mean radius, number density, volume fraction, and matrix composition evolution during isothermal annealing with reasonable accuracy. The possible reduction of the mobility of Cu-rich clusters due to additional alloying elements in Fe-Cu based steels is discussed

A study of copper precipitation in Fe-Cu and Fe-Cu-Ni model alloys

SIGLEAvailable from British Library Document Supply Centre- DSC:D175441 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Per IMERSLUND: Un voluntario noruego en la Guerra Civil española, edición a cargo de Mariano González Campo, Madrid, SND Editores, 2020, 224 pp., ISBN: 9788412212532

Reseña de la obra de Per IMERSLUND: Un voluntario noruego en la Guerra Civil española, edición a cargo de Mariano González Campo, Madrid, SND Editores, 2020, 224 pp., ISBN: 9788412212532