Slip systems and orientation dependence of yield stress in high purity molybdenum single crystals at 4.2 K and 77 K

Kitajima, K.; Aono, Yasuhisa; Kuramoto, Eiichi

doi:10.1016/0036-9748(81)90278-7

Cited by 30 publications

(49 citation statements)

References 13 publications

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“…In this respect, the present model is similar to the threefold symmetric dissociation model ͑e.g., Kroupa and Vitek 26 ͒, which also considers only the symmetry but not the periodicity of the lattice. In spite of the simplicity of the present model, the obtained relations of c ϪT, c Ϫ, and Ϫ describe well the overall trends of the experiments on W, 27 Mo, 28,29 Ta, 30 Nb, 31 and ␣-Fe. 32 This implies that the plastic anisotropy essentially stems from the geometry or the symmetry of the screw dislocation in the bcc lattice, irrespective of the details of the core structure and also the shape of the potential.…”

Section: Discussionsupporting

confidence: 76%

Motion of a screw dislocation in a two-dimensional Peierls potential

1997

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Motion of a screw dislocation in a crystal lattice occurs by kink pair formation in a two-dimensional Peierls potential. Employing the line-tension model of a dislocation, the saddle-point configuration of a nonplanar kink pair in three-dimensional space and the associated activation energy are calculated. The method is applied to a ͗111͘ screw dislocation in a bcc lattice assuming a threefold periodic sinusoidal Peierls potential in the ͑111͒ plane. In this potential the dislocation can nucleate a kink pair from one stable straight configuration towards any of the three adjacent ones. Depending on the direction of the applied stress the relative frequencies of the three activation processes determine the temperature dependence of the critical flow stress and the direction of total slip. The calculations reproduce well the plastic anisotropy of bcc transition metals.

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Section: Discussionsupporting

confidence: 76%

Motion of a screw dislocation in a two-dimensional Peierls potential

1997

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“…= 8.5 " 10 #4 s -1 are from [45]. [50,52,53]. Hence, it is characteristic for the thermally activated overcoming of the Peierls barrier related to the non-planar cores of screw dislocations.…”

Section: Comparisons With Experimental Measurements Of the Temperaturmentioning

confidence: 99%

Multiscale modeling of plastic deformation of molybdenum and tungsten. III. Effects of temperature and plastic strain rate

Gröger

Vítek

2008

Acta Materialia

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In this paper we develop a link between the atomic-level modeling of the glide of 1/2〈111〉 screw dislocations at 0 K and the thermally activated motion of these dislocations via nucleation of pairs of kinks. For this purpose, we introduce the concept of a hypothetical Peierls barrier, which reproduces all the aspects of the dislocation glide at 0 K resulting from the complex response to non-glide stresses and expressed in a compact form by the yield criteria advanced in Part II. To achieve this the barrier is dependent not only on the crystal symmetry and interatomic bonding but also on the applied stress tensor. Standard models are then employed to evaluate the activation enthalpy of kink-pairs formation, which is now also a function of the full applied stress tensor. The transition states theory links then this mechanism with the temperature and strain rate dependence of the yield stress.

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“…While direct experimental observations of the cores of screw dislocations are precarious [42,43], such core spreading has been found in all atomistic calculations (for reviews see [3,[44][45][46][47][48][49][50][51]). In all these studies the core was found to spread into three {110} planes, specifically (101) , (011) and (110) for the 1/2 [111] dislocation.…”

Section: Introductionmentioning

confidence: 99%