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Crystallinity, Crystalline Quality, and Microstructural Ordering in Boron Nitride Fibers
Author(s) -
Bernard Samuel,
Chassagneux Fernand,
Berthet MariePaule,
Cornu David,
Miele Philippe
Publication year - 2005
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2005.00318.x
Subject(s) - materials science , microstructure , crystallite , crystallinity , composite material , amorphous solid , boron nitride , modulus , fiber , crystallography , metallurgy , chemistry
A qualitative and quantitative analysis of the microtexture/microstructure in several experimental boron nitride fibers was investigated by X‐ray diffraction and electron microscopy according to their mechanical properties. Young's modulus was controlled by grain orientation. The disordered microstructure of low modulus fibers consisted of amorphous regions and nanometer‐sized crystallites arranged in a wide range of orientation. In contrast, high modulus samples showed a coarse‐grained microtexture in which crystallites were ordered in a meso‐hexagonal arrangement along the fiber ‐axis. Cracks were easily propagated as crystallinity increased, leading to decreased failure strain. The strength‐microstructure relationship was obscured by the fiber porosity and defects.