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

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.

Investigation of slip system activity in iron at room temperature by SEM and AFM in-situ tensile and compression tests of iron single crystals

“…According to these experimental observations, at least concerning the BCC commercially pure iron crystals strained at room temperature and at low strain rates, the f112g slip planes appear to participate per se in the crystallographic slip, both in the twining (easy) and in the anti-twining (uneasy) directions of slip. In the several tested cases when the f110g slip type is not active, the orientation of the observed slip lines observed at the microscopic level does not appear to correspond to a mixture of collinear f110g planes, as suggested by Marichal et al (2013). No intermediate ''curved'' slip lines were observed, except some departures from the planar segments due to cross-slip events from the f112g to the f110g plane.…”

Microcompression of brittle and anisotropic crystals: recent advances and current challenges in studying plasticity in hard materials

“…In BCC metals, fundamental aspects of dislocation core structure, stress tensor dependence, and resulting non-Schmid behavior, are also still under investigation. [5,6] However, in all of these materials, the availability of large-grained or single crystals with sufficient purity has scarcely been a problem, nor has the ability to deform such samples under carefully controlled conditions. Suitable investigations by conventional, analytical and high-resolution microscopy techniques have also been carried out whenever new methods have allowed researchers to dive deeper into the physics of their plastic deformation.…”

Dislocation junctions as indicators of elementary slip planes in body-centered cubic metals

“…Recently, Marichal et al [19,20] performed in situ Laue diffraction experiments in W micropillars, combined with detailed slip trace analysis to investigate slip for orientations near the ½011 corner of the stereographic triangle. They interpret the slip traces in terms of composite f110g slip.…”