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{110} Slip with {112} slip traces in bcc Tungsten.

Marichal C, Van Swygenhoven H, Van Petegem S, Borca C - Sci Rep (2013)

Bottom Line: Here with in-situ Laue diffraction experiments during micro-compression we demonstrate that when two {110} planes containing the same slip direction experience the same resolved shear stress, sharp slip traces are observed on a {112} plane.When however the {110} planes are slightly differently stressed, macroscopic strain is measured on the individual planes and collective cross-slip is used to fulfill mechanical boundary conditions, resulting in a zig-zag or broad slip trace on the sample surface.We anticipate that such dynamics can occur in polycrystalline metals due to local inhomogeneous stress distributions and can cause unusual slip transfer among grains.

View Article: PubMed Central - PubMed

Affiliation: Materials Science and Simulation, NUM/ASQ, Paul Scherrer Institut, Villigen PSI, Switzerland.

ABSTRACT
While propagation of dislocations in body centered cubic metals at low temperature is understood in terms of elementary steps on {110} planes, slip traces correspond often with other crystallographic or non-crystallographic planes. In the past, characterization of slip was limited to post-mortem electron microscopy and slip trace analysis on the sample surface. Here with in-situ Laue diffraction experiments during micro-compression we demonstrate that when two {110} planes containing the same slip direction experience the same resolved shear stress, sharp slip traces are observed on a {112} plane. When however the {110} planes are slightly differently stressed, macroscopic strain is measured on the individual planes and collective cross-slip is used to fulfill mechanical boundary conditions, resulting in a zig-zag or broad slip trace on the sample surface. We anticipate that such dynamics can occur in polycrystalline metals due to local inhomogeneous stress distributions and can cause unusual slip transfer among grains.

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Related in: MedlinePlus

In-situ results of a W single crystal with [256] compression axis.(a) Stress-strain curve (b) Two dimensional representation of the (101) diffraction spot. The white lines present the expected rotation direction for slip on the indicated planes. (c) Zoom-in on the path followed by the (101) spot during the compression, the pattern numbers correspond to the stress values shown in (a). (d) Zoom-in of the very jerky part of the spot path surrounded in green on (c). (e) this back and forward movement of the peak along the rotation direction for (101) and (110) slip is shown in more detail for the (013) diffraction spot and with a different viewing angle. (f) Two views of the slip trace visible on SEM pictures taken after deformation.
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f3: In-situ results of a W single crystal with [256] compression axis.(a) Stress-strain curve (b) Two dimensional representation of the (101) diffraction spot. The white lines present the expected rotation direction for slip on the indicated planes. (c) Zoom-in on the path followed by the (101) spot during the compression, the pattern numbers correspond to the stress values shown in (a). (d) Zoom-in of the very jerky part of the spot path surrounded in green on (c). (e) this back and forward movement of the peak along the rotation direction for (101) and (110) slip is shown in more detail for the (013) diffraction spot and with a different viewing angle. (f) Two views of the slip trace visible on SEM pictures taken after deformation.

Mentions: So far the Laue results confirm that in the athermal regime slip can be described as composed of elementary steps on {110} planes. This is however not the case in orientations for which the Schmid factors on the most stressed {110] planes differ slightly. The character of slip changes drastically when a [256] oriented pillar is compressed. Figure 3a shows the stress-strain curve of such a pillar, Figure 3b the (101) Laue reflection as well as the possible rotation directions plotted with white lines. A zoom-in of the orange square is shown on Figure 3c, where the path followed by the (101) spot during loading is presented by the yellow line. The numbers along the Laue path correspond with the numbers shown on the stress-strain curve. During initial loading till 650 MPa (corresponding with pattern 35), the (101) Laue peak moves slightly in a direction that does not correspond with any crystallographic slip.


{110} Slip with {112} slip traces in bcc Tungsten.

Marichal C, Van Swygenhoven H, Van Petegem S, Borca C - Sci Rep (2013)

In-situ results of a W single crystal with [256] compression axis.(a) Stress-strain curve (b) Two dimensional representation of the (101) diffraction spot. The white lines present the expected rotation direction for slip on the indicated planes. (c) Zoom-in on the path followed by the (101) spot during the compression, the pattern numbers correspond to the stress values shown in (a). (d) Zoom-in of the very jerky part of the spot path surrounded in green on (c). (e) this back and forward movement of the peak along the rotation direction for (101) and (110) slip is shown in more detail for the (013) diffraction spot and with a different viewing angle. (f) Two views of the slip trace visible on SEM pictures taken after deformation.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3757353&req=5

f3: In-situ results of a W single crystal with [256] compression axis.(a) Stress-strain curve (b) Two dimensional representation of the (101) diffraction spot. The white lines present the expected rotation direction for slip on the indicated planes. (c) Zoom-in on the path followed by the (101) spot during the compression, the pattern numbers correspond to the stress values shown in (a). (d) Zoom-in of the very jerky part of the spot path surrounded in green on (c). (e) this back and forward movement of the peak along the rotation direction for (101) and (110) slip is shown in more detail for the (013) diffraction spot and with a different viewing angle. (f) Two views of the slip trace visible on SEM pictures taken after deformation.
Mentions: So far the Laue results confirm that in the athermal regime slip can be described as composed of elementary steps on {110} planes. This is however not the case in orientations for which the Schmid factors on the most stressed {110] planes differ slightly. The character of slip changes drastically when a [256] oriented pillar is compressed. Figure 3a shows the stress-strain curve of such a pillar, Figure 3b the (101) Laue reflection as well as the possible rotation directions plotted with white lines. A zoom-in of the orange square is shown on Figure 3c, where the path followed by the (101) spot during loading is presented by the yellow line. The numbers along the Laue path correspond with the numbers shown on the stress-strain curve. During initial loading till 650 MPa (corresponding with pattern 35), the (101) Laue peak moves slightly in a direction that does not correspond with any crystallographic slip.

Bottom Line: Here with in-situ Laue diffraction experiments during micro-compression we demonstrate that when two {110} planes containing the same slip direction experience the same resolved shear stress, sharp slip traces are observed on a {112} plane.When however the {110} planes are slightly differently stressed, macroscopic strain is measured on the individual planes and collective cross-slip is used to fulfill mechanical boundary conditions, resulting in a zig-zag or broad slip trace on the sample surface.We anticipate that such dynamics can occur in polycrystalline metals due to local inhomogeneous stress distributions and can cause unusual slip transfer among grains.

View Article: PubMed Central - PubMed

Affiliation: Materials Science and Simulation, NUM/ASQ, Paul Scherrer Institut, Villigen PSI, Switzerland.

ABSTRACT
While propagation of dislocations in body centered cubic metals at low temperature is understood in terms of elementary steps on {110} planes, slip traces correspond often with other crystallographic or non-crystallographic planes. In the past, characterization of slip was limited to post-mortem electron microscopy and slip trace analysis on the sample surface. Here with in-situ Laue diffraction experiments during micro-compression we demonstrate that when two {110} planes containing the same slip direction experience the same resolved shear stress, sharp slip traces are observed on a {112} plane. When however the {110} planes are slightly differently stressed, macroscopic strain is measured on the individual planes and collective cross-slip is used to fulfill mechanical boundary conditions, resulting in a zig-zag or broad slip trace on the sample surface. We anticipate that such dynamics can occur in polycrystalline metals due to local inhomogeneous stress distributions and can cause unusual slip transfer among grains.

Show MeSH
Related in: MedlinePlus