Original paper

TEM study of mechanical twinning in experimentally deformed chalcopyrite (CuFeS2) single crystals

Hennig-Michaeli, Christa; Couderc, Jean-Jacques

European Journal of Mineralogy Volume 1 Number 2 (1989), p. 295 - 314

19 references

published: May 3, 1989
manuscript accepted: Nov 30, 1988
manuscript received: Apr 9, 1988

DOI: 10.1127/ejm/1/2/0295

BibTeX file

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Abstract {102} twins are common internal structures in chalcopyrite grains of metamorphic ores. A chalcopyrite crystal has been compressed 3.8 % along the [100] direction at 400 °C (0.58 Tm) under 300 MPa confining pressure. In a broad shear band, the deformed crystal contains two sets of twins with the twin planes (102) and (102). The individual twins appear to be platelets that can coalesce to brick-shaped twin domains. They distort the sample surfaces only slightly. TEM observations reveal quite different microfabrics in the matrix and the twins. Within the matrix, dislocation glide prevails with {112} slip as the predominant glide mode. The dislocations are dissociated within their glide planes. Numerous small loops in (001) planes with b parallel to [021] and [021ֿ] indicate bulk diffusion. The twins contain a complex three-dimensional dislocation network with a dislocation density higher than that within the matrix. The predominant defects are curved dislocations which are not confined to specific planes, as well as straight dislocation segments parallel to and small loops in the (001) planes. Contrast analyses reveal Burgers vectors parallel to . In general, the dislocations are not dissociated. Presumably they are isolated partials with b = 1/4 . Dislocation motion is mainly controlled by climb processes. The twins are considered to be strain-induced transformation twins proceeding from interstitial loops in the (001) planes of the matrix.


chalcopyriteexperimental deformationTEMdislocationstransformation twins