The ultimate failure of boron carbide in a ballistic event depends on a number of elastic and inelastic processes whose length scales vary from the atomistic to macroscopic, including the various deformation modes, damage nucleation and accumulation processes, from the atomic structure level through the micro-structural to the macro-structural level. The expanded use of boron carbide as an armor ceramic is dependant upon understanding these mechanisms and using this knowledge to design and produce improved boron carbide. In recent years, ARL, in collaboration with other researchers, has identified previously unknown inelastic phenomena in boron carbide including solid-state amorphization at the nano-scale and subsequent shear localization at the microstructural level. Recent characterization of boron carbide powders has raised questions concerning the presence of B13C2. the stoichiometry of B4C. and the accuracy of the commonly accepted phase diagrams. In addition, the characterization of commercial boron carbide ceramics has revealed the presence of a very wide range of microstructural defects. These results have led to density functional theory (DFT) calculations on the stability of various boron carbide polymorphs, high-pressure phase transition studies, and raised questions concerning the influence of stoichiometry and microstructural defects on quasi-static and dynamic mechanical properties. A review of recent findings and possible interpretations will be discussed.
The possible roles of stoichiometry, microstructure, and defects on the mechanical behavior of boron carbide
2009
10 Seiten, 22 Quellen
Conference paper
English
Amorphisierung , amorph-kristalliner Übergang , Anwendung in der Wehrtechnik , Atomstruktur , Beschussprüfung , Borcarbid , Bruchgrenze , Dichtefunktion , elastoplastische Bruchmechanik , Festkörperreaktion , Gitterfehler , militärische Ausrüstung , Nichtoxidkeramik , Phasenumwandlung , Schlagbeanspruchung , Stöchiometrie , Übersichtsdarstellung , Wahrscheinlichkeitsrechnung , Dichtefunktionstheorie
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