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Raman microspectroscopy of nanocrystalline and amorphous phases in hardness indentations
Author(s) -
Kailer Andreas,
Nickel Klaus G.,
Gogotsi Yury G.
Publication year - 1999
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/(sici)1097-4555(199910)30:10<939::aid-jrs460>3.0.co;2-c
Subject(s) - indentation , materials science , amorphous solid , nanocrystalline material , nanoindentation , raman spectroscopy , phase (matter) , brittleness , composite material , indentation hardness , ceramic , quartz , crystallography , microstructure , nanotechnology , optics , chemistry , physics , organic chemistry
During hardness indentation, materials are subjected to highly l highly localized stresses. These stresses not only cause crack formation and plastic deformation by dislocation gliding, but a complete change of the crystal structure and formation of amorphous phases or high‐pressure polymorphs can occur in the zone of maximum contact stresses. Such contact‐induced phase transformations were observed in hard and brittle materials including semiconductors (Si, Ge, GaAs and InSb) and common ceramic materials such as SiC and SiO 2 (α‐quartz and silica glass). A prime tool for their investigation is the Raman microspectroscopy of hardness indentations. In Si and Ge, there is an initial transformation to metallic high‐pressure phases upon hardness indentation and a subsequent formation of crystalline, nanocrystalline, or amorphous phases depending on the conditions of the hardness test, in particular the unloading rate. A phase transformation occurs also in InSb, whereas the results for GaAs do not give sufficient evidence for phase transformations. Indentation‐induced amorphization has been observed in SiC and quartz. Even diamond has been shown to undergo amorphization and phase transformation under nonhydrostatic stress conditions imposed by indentation tests. Copyright © 1999 John Wiley & Sons, Ltd.