Plastic Deformation of Approximants: Dislocations vs. Phason Lines

1998 ◽  
Vol 553 ◽  
Author(s):  
H. Klein ◽  
M. Feuerbacher ◽  
P. Schall ◽  
K. Urban

AbstractDeformation experiments were performed on single crystals of the ξ-AIPdMn approximant in bending geometry at high temperature. Two different mechanisms of plastic deformation are shown to exist in this phase: one based on dislocations and another novel mechanism based on the motion of phason lines. Burgers vector and line directions of dislocations were determined. Phason lines are shown to build a periodic lattice. The interaction of a dislocation with the phason line lattice results in dislocations on another length scale. This meta-dislocation in the periodic phason line lattice has a Burgers vector of magnitude 165 Å. The relative importance of phason lines and dislocations for the plastic deformation is discussed as a function of the orientation of the sample with respect to the bending geometry.

2003 ◽  
Vol 23 (13) ◽  
pp. 2183-2191 ◽  
Author(s):  
Angela Gallardo-López ◽  
Diego Gómez-Garcı́a ◽  
Julián Martı́nez-Fernández ◽  
Arturo Domı́nguez-Rodrı́guez

1978 ◽  
Vol 21 (7) ◽  
pp. 929-932
Author(s):  
V. V. Starenchenko ◽  
V. S. Kobytev ◽  
�. V. Kozlov ◽  
L. E. Popov

Author(s):  
M.M. Myshlyaev ◽  
I.I. Khodos ◽  
O.N. Senkov ◽  
Yu.A. Romanov

The subboundary structure corresponding to the high temperature steady-state creep of molybdenum single crystals is formed by both regular sites of dislocation nets and walls, various in structure and composition, (the nets are formed by two, three, five and six dislocation sets having different values of the angles between the Burgers vector Ḇ and the dislocation line ū ; the walls are formed by one, two and three sets of edge and mixed dislocations; the Burgers vectors of the dislocations are I/2 <III> and, <I00>) and by the sites of a more complex and less regular structure. Several of these are considered below.Fig.I represents a subboundary formed by five dislocation sets.Its regular sites (nets) can be formed by means of interaction of dislocations I and 4 with dislocations 2 (fig.2a). In several irregular sites (fig.I and 2b) no dislocations 2 are seen to be present, and neither dislocations 3 and 5 arisen from the reactions of dislocations 2 with dislocations I and 4.


2000 ◽  
Vol 646 ◽  
Author(s):  
Kazuhiro Ito ◽  
Hironori Yoshioka ◽  
Masaharu Yamaguchi

ABSTRACTMoSi2 has a great potential for very high temperature structural applications. Plastic deformation of MoSi2 single crystals with the C11b structure is extremely anisotropic. It is caused by non-Schmid behavior of slip on {013}<331> with the higher CRSS values for orientations closer to [001]. In order to provide better understanding of key factors on such non-Schmid behavior in MoSi2 (c/a=2.45), we chose PdZr2 with a c/a axial ratio higher than 3 (c/a=3.30) and characterized the plastic deformation. Compression tests were conducted at various temperatures along [001], [010] and [110] axes. Slip on {013}<100> has the shortest Burgers vector and the largest interplanar spacing in PdZr2 and was observed to be activated for [110] with the lowest CRSS. While slip on {013}<331> can be activated even at -196°C for [001]. Although {013}<331> slip has the same Schmid factors for [001] and [010], the yield stress of the [010]-oriented crystals is about twice higher than that of the [001]-oriented crystals. Thus non-Schmid behavior of slip on {013}<331> is also observed in PdZr2, and the manner is opposite to that in MoSi2. Plastic anisotropy in the C11b structure will be discussed in terms of the c/a axial ratio.


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