Approximant phases, phason planes and domain-boundary networks in Alâ^'Niâ^'Rh alloys
Authors: Chen, Y. H.1; Sun, W.1; Zhang, Z.1
Source: Philosophical Magazine Letters, Volume 86, Number 12, December 2006 , pp. 817-827(11)
Publisher: Taylor and Francis Ltd
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Abstract:
<p>Structurally complicated ξâ-²- and ξ-phases have been found, for the first time, in as-cast Al<sub>73</sub>Ni<sub>5</sub>Rh<sub>22</sub> and Al<sub>75</sub>Ni<sub>15</sub>Rh<sub>10</sub> alloys. The lattice parameters of these two phases were determined by means of electron diffraction and high-resolution transmission electron microscopy (HREM). These two phases have similar orthorhombic structures but with different lattice parameters of <i>a</i>â-‰=â-‰23.2â-‰Ã…, <i>b</i>â-‰=â-‰16.4â-‰Ã…, <i>c</i>â-‰=â-‰12.0â-‰Ã… for the ξâ-²-phase and <i>a</i>â-‰=â-‰20.3â-‰Ã…, <i>b</i>â-‰=â-‰16.4â-‰Ã…, <i>c</i>â-‰=â-‰14.8â-‰Ã… for the ξ-phase. A new two-dimensional domain-boundary network has also been observed in these two phases. Domain boundaries with normals closely parallel to the [001] direction are actually phason planes represented by a translation vector of <b>r</b>â-‰=(1/2)<b>a</b>â-‰+(1/2Ï,,)<b>c</b> in the ξâ-²-phase and <b>r</b>=±(1/2Ï,,<sup>2</sup>) <b>a</b>â-‰+(Ï,,/2)<b>c</b> in the ξ-phase, whereas the newly-found wide and zigzag boundaries perpendicular to the above set were attributed from the step-like boundary structures of domains related by a translation vector of <b>r</b>â-‰=(1/Ï,,)((1/2)<b>a</b>â-‰+(1/2Ï,,)<b>c</b>). The structural difference between the two types of planar faults is discussed.</p>Document Type: Research article
DOI: 10.1080/09500830601057934
Affiliations: 1: Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, 100 Pingle Yuan, Chao Yang District, Beijing 100022, China
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