Differences between Crystal Slip and Twinning

Comparison between crystal slip and twinning can be done in aspects like defect type, seen in, change in crystal axis, stress requirement, visibility and for occurrence threshold value of stress.

1Crystal slip is a line defect.Twinning is a surface defect grain boundary defect.
2During slip, all atoms in a block move the same distance.During twinning, the atoms in each successive plane in a block move through different distances proportional to their distance from twinning plane.
3Slip is commonly observed in Body centered Cubic (BCC) and Face Centered Cubic (FCC) metals.Twinning is commonly observed in Hexagonal Close Packing (HCP) metals.
4After the slip, the crystal axis remains the same.After twinning, the crystal axis is deformed.
5The slipped crystal lattice has the same orientation.The twinned crystal lattice is the minor image of the original lattice.
6The stress required for slip is comparatively low.The stress required for twinning is comparatively more.
7The stress necessary to propagate slip is usually higher than the stress required to start slip.The stress necessary to propagate twinning is lesser than that required starting it.
8Slip can be seen as thin lines when viewed under microscope.Twinning can be seen as broad lines when viewed under microscope.
9For slipping to occur, a threshold valve of stress called critical resolved shear stress is required.For twinning to occur, no such threshold valve of stress is required.

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