Effect of Misorientation on the Compression of Highly Anisotropic Single‐Crystal Micropillars

Abstract

The effect of crystal misorientation, geometrical tilt, and contact misalignment on the compression of highly anisotropic single crystal micropillars was assessed by means of crystal plasticity finite element simulations. The investigation was focused in single crystals with the NaCl structure, like MgO or LiF, which present a marked plastic anisotropy as a result of the large difference in the critical resolved shear stress between the “soft” {110}〈110〉 and the “hard” {100}〈110〉 active slip systems. It was found that contact misalignment led to a large reduction in the initial stiffness of the micropillar in crystals oriented in the soft and hard direction. The crystallographic tilt did not modify, however, the initial crystal stiffness. From the viewpoint of the plastic response, none of the effects analyzed led to significant differences in the flow stress when the single crystals were oriented along the “soft” [100] direction. Large differences were found, however, if the single crystal was oriented in the “hard” [111] direction as a result of the activation of the soft slip system. Numerical simulations were in very good agreement with experimental literature data.

Size-dependent plasticity in KCl and LiF single crystals: influence of orientation, temperature, pre-straining and doping

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High temperature micropillar compression of Al/SiC nanolaminates

“…The initial loading slope of the stress-strain curves at 23 °C and 100 °C was much more compliant than that expected from purely elastic loading. This behavior was attributed to the local plastic yielding at the top of the micropillar, because of slight misalignments between the micropillar surface and the flat punch, before full contact is established between the two [37]. This effect is clearly seen in the variation in elastic modulus of the micropillar, determined from the slope of the unloading steps during the test, as a function of the applied displacement (Fig.…”

Relating fracture toughness to micro-pillar compression response for a laser powder bed additive manufactured bulk metallic glass

“…The observed variation cannot be wholly explained from either the complex geometry at the post-base in the Sneddon correction and any misalignments during compression [40], which would have been observable during in situ testing. Generally, increased compliance exists during the initial part of the elastic loading due to small misalignments and/or surface irregularities [42], which may in part explain the lower result for AC, but does not fully explain such a large deviation from the expected macroscopic result. Next, using a 0.2% strain offset yield criterion (Fig.…”