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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 result of a second W micro-pillar with a compression axis along [256].(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 numbers correspond to the stress values shown in (a); (d) Two views on the slip trace visible on SEM pictures taken after deformation.
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f4: In-situ result of a second W micro-pillar with a compression axis along [256].(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 numbers correspond to the stress values shown in (a); (d) Two views on the slip trace visible on SEM pictures taken after deformation.

Mentions: Among the pillars studied, other combinations of collective cross-slip have been observed. Figure 4a shows the stress-strain curve of another [256] oriented pillar together with numbers of corresponding Laue patterns. The path of the (101) diffraction spot is shown in Figure 4b together with a projection of the possible rotation directions. The region of interest is zoomed in Figure 4c. Till pattern 32 corresponding with 600 MPa Laue spots broaden and simultaneously rotate about 0.36° degree this time in the direction corresponding to slip in the (110) plane. Between pattern 30 and 40 there is a discontinuous change of rotation direction indicating a rotation corresponding with (211) i.e. resulting from composed slip on the (110) and (101) planes. Between pattern 40 and 60 the Laue peak moves predominantly according to slip on (110) after which the spot clearly changes direction and rotates predominantly according to slip on (101), suggesting collective cross-slip. At pattern 83 until the end of the load, the peak changes again and follows a direction suggesting combined slip on (110) and (101). Note that at pattern 85, the global rotation evidenced by Laue corresponds to a rotation along the (211) line.


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

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

In-situ result of a second W micro-pillar with a compression axis along [256].(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 numbers correspond to the stress values shown in (a); (d) Two views on 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

f4: In-situ result of a second W micro-pillar with a compression axis along [256].(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 numbers correspond to the stress values shown in (a); (d) Two views on the slip trace visible on SEM pictures taken after deformation.
Mentions: Among the pillars studied, other combinations of collective cross-slip have been observed. Figure 4a shows the stress-strain curve of another [256] oriented pillar together with numbers of corresponding Laue patterns. The path of the (101) diffraction spot is shown in Figure 4b together with a projection of the possible rotation directions. The region of interest is zoomed in Figure 4c. Till pattern 32 corresponding with 600 MPa Laue spots broaden and simultaneously rotate about 0.36° degree this time in the direction corresponding to slip in the (110) plane. Between pattern 30 and 40 there is a discontinuous change of rotation direction indicating a rotation corresponding with (211) i.e. resulting from composed slip on the (110) and (101) planes. Between pattern 40 and 60 the Laue peak moves predominantly according to slip on (110) after which the spot clearly changes direction and rotates predominantly according to slip on (101), suggesting collective cross-slip. At pattern 83 until the end of the load, the peak changes again and follows a direction suggesting combined slip on (110) and (101). Note that at pattern 85, the global rotation evidenced by Laue corresponds to a rotation along the (211) line.

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