Slip in Single Crystals
AimsBefore you startIntroductionSlip geometry: the critical resolved shear stressGeometry during slipSlip in HCP metals 1: slip systemsSlip in HCP metals 2: application of Schmid's LawSlip in HCP metals 3: calculation of forcesSlip in HCP metals 4: observing slip in cadmiumVideo clips of slip in a single cadmium crystalExercise: Determination of the critical resolved shear stress for slip in cadmiumSlip in CCP metalsSummaryQuestionsGoing furtherTLP creditsTLP contentsShow all contentViewing and downloading resourcesAbout the TLPsTerms of useFeedbackCredits Print this page

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# Geometry during slip

Two conditions restrict the geometry of a crystal as slip proceeds:

- the
*spacing of the planes*remains constant; - the
*number of planes in the specimen*is conserved.

These give rise to two important relationships that describe the way that the orientation of slip planes and slip directions changes as slip proceeds:

**l cos φ**is constant, so that as the specimen length l increases, the angle between the slip plane normal and the tensile axis approaches 90°**l sin λ**is constant, so that as l increases, the angle between the slip direction and the tensile axis approaches zero.

If a crystal is extended from length l_{0} to length l_{1}, then the angles φ and λ are related as follows:

l |