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Metallic Systems (metallic + system)

Distribution by Scientific Domains
Physics and Astronomy42%

Selected Abstracts

Phase Diagrams and Glass Formation in Metallic Systems,

ADVANCED ENGINEERING MATERIALS, Issue 6 2007
M. Baricco
Abstract The basic thermodynamic aspects of glass-formation in metallic systems are reviewed. In particular, the specific features of a phase diagram with respect to glass-formation are evidenced. On the basis of the regular solution model, the effect of various thermodynamic quantities on the free energy difference between undercooled liquid and crystal phases are outlined. In order to describe the amorphous phase, a specific heat difference between liquid and solid phases in the undercooling regime is introduced in the CALPHAD assessment of various binary systems. The glass-transition is described as a second order transition. Examples are given for different systems, including Fe-B and Cu-Mg. From the description of the free energy of various phases as a function of composition and temperature, the driving forces for nucleation of crystal phases and the T0 curves are estimated. [source]

Characterisation and Modelling of Non-Isothermal Precipitation in Metallic Systems,

ADVANCED ENGINEERING MATERIALS, Issue 12 2006
A. Deschamps
During the process of most age hardening metallic alloys, non-isothermal precipitation plays a key role. The non-isothermal nature of precipitation processes can be either imposed by constraints of the process route (e.g. precipitation during coiling of NbC in steels, or precipitation in weld heat affected zones), or it can be found as the optimal pathway to the desired properties (e.g. multi-step heat treatments of aluminium alloys). The presented work addresses both on an experimental and on a modelling point of view some of these effects, both in aluminium alloys (the Al-Zn-Mg and Al-Zr-Sc systems) and in a Fe-Cu alloy. [source]

Muffin-Tin Orbital Wannier-Like Functions for Insulators and Metals

CHEMPHYSCHEM, Issue 9 2005
Eva Zurek
Abstract Herein, we outline a method that is able to generate truly minimal basis sets that accurately describe either a group of bands, a band, or even just the occupied part of a band. These basis sets are the so-called NMTOs, muffin-tin orbitals of order N. For an isolated set of bands, symmetrical orthonormalization of the NMTOs yields a set of Wannier functions that are atom-centered and localized by construction. They are not necessarily maximally localized, but may be transformed into those Wannier functions. For bands that overlap others, Wannier-like functions can be generated. It is shown that NMTOs give a chemical understanding of an extended system. In particular, orbitals for the , and , bands in an insulator, boron nitride, and a semimetal, graphite, will be considered. In addition, we illustrate that it is possible to obtain Wannier-like functions for only the occupied states in a metallic system by generating NMTOs for cesium. Finally, we visualize the pressure-induced s,d transition. [source]

Phase Diagrams and Glass Formation in Metallic Systems,

ADVANCED ENGINEERING MATERIALS, Issue 6 2007
M. Baricco
Abstract The basic thermodynamic aspects of glass-formation in metallic systems are reviewed. In particular, the specific features of a phase diagram with respect to glass-formation are evidenced. On the basis of the regular solution model, the effect of various thermodynamic quantities on the free energy difference between undercooled liquid and crystal phases are outlined. In order to describe the amorphous phase, a specific heat difference between liquid and solid phases in the undercooling regime is introduced in the CALPHAD assessment of various binary systems. The glass-transition is described as a second order transition. Examples are given for different systems, including Fe-B and Cu-Mg. From the description of the free energy of various phases as a function of composition and temperature, the driving forces for nucleation of crystal phases and the T0 curves are estimated. [source]

Quantum criticality and novel phases: Summary and outlook

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 3 2010
A. J. Schofield
Abstract This conference summary and outlook provides a personal overview of the topics and themes of the August 2009 Dresden meeting on quantum criticality and novel phases. The dichotomy between the local moment and the itinerant views of magnetism is revisited and refreshed in new materials, new probes, and new theoretical ideas. New universality and apparent zero temperature phases of matter move us beyond the old ideas of quantum criticality. This is accompanied by alternative pairing interactions and as yet unidentified phases developing in the vicinity of quantum critical points. In discussing novel order, the magnetic analogs of superconductivity are considered as candidate states for the hidden order that sometimes develops in the vicinity of quantum critical points in metallic systems. These analogs can be thought of as "pairing" in the particle,hole channel and are tabulated. This analogy is used to outline a framework to study the relation between ferromagnetic fluctuations and the propensity of a metal to nematic type phases , which at weak coupling correspond to Pomeranchuk instabilities. This question can be related to the fundamental relations of Fermi liquid theory. [source]

Core-level shifts in complex metallic systems from first principle

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 11 2006
Weine Olovsson
Abstract We show that core-level binding energy shifts (CLS) can be reliably calculated within density functional theory. The scheme includes both the initial (electron energy eigenvalue) as well as final state (relaxation due to core-hole screening) effects in the same framework. The results include CLS as a function of composition in substitutional random bulk and surface alloys. Sensitivity of the CLS to the local chemical environment in the bulk and at the surface is demonstrated. A possibility to use the CLS for structural determination is discussed. Finally, an extension of the model is made for Auger kinetic energy shift calculations. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Statistics of charge transfer through impurities in strongly correlated 1D metals,

ANNALEN DER PHYSIK, Issue 10-11 2007
A. Komnik
Abstract We review recent advances in the field of full counting statistics (FCS) of charge transfer through impurities imbedded into strongly correlated one-dimensional metallic systems, modelled by Tomonaga-Luttinger liquids (TLLs). We concentrate on the exact analytic solutions for the cumulant generating function, which became available recently and apply these methods in order to obtain the FCS of a non-trivial contact between two crossed TLL. [source]