Abstract

Sanjay Kumar Bhagat

A critical analysis in single crystals of a decagonal phase in Al-Cu-Co-Si quaternary system has been presented. X-ray diffraction and convergent beam electron diffraction patterns of the power samples confirmed the structures to be decagonal quasi crystals. Diffuse streaks along symmetric directions around the fundamental spots were observed in the diffraction patterns. Bright and dark field images showed continuous lines or striations lying perpendicular to the direction of diffuse streaking. The striation contrast appears to be originating from anti-phase boundary in the decagonal superstructures. The diffuse streaks seem to be a characteristic feature of a partially ordered decagonal superlattice structures

Decagonal quasi crystals; diffraction patterns; striation; anti-phase boundary

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