Dissemination of IT for the Promotion of Materials Science (DoITPoMS)

DoITPoMS Teaching & Learning Packages Mechanisms of Plasticity Questions
Mechanisms of Plasticity AimsBefore you startIntroductionDislocation generationDislocation interactions Sessile dislocationsClimb and cross slipDislocation intersections to form jogs and kinksDeformation of a single crystalForest hardeningContinuum models describing the true stress-strain curvesGrain boundary hardening of poly-crystalsSummaryQuestionsGoing further
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Questions

Quick questions

You should be able to answer these questions without too much difficulty after studying this TLP. If not, then you should go through it again!

  1. What is the ratio of the minimum shear stress required to operate a Frank-Read source for work-hardened copper (ρ = 1014 m-2) and annealed copper (ρ = 1010 m-2)?

    a 1
    b 10
    c 100
    d 1000

  2. Which of the following about cross-slip is true?

    a Cross-slip is favored by a high stacking-fault energy
    b Cross-slip is favored by a low stacking-fault energy
    c Edge dislocation can bypass obstacles via cross-slip
    d None of the above

  3. Which type of intersection is most important to work hardening?

    a edge-screw intersection
    b edge-edge intersection
    c screw-screw intersection
    d none of the above

  4. Which of the following is not a pinning site in forest hardening?

    a Lomer lock
    b jogs
    c kinks
    d precipitates

  5. Which of the following about poly-crystals is/are true?

    a Poly-crystals do not exhibit any easy glide
    b Poly-crystals tend to have higher yield stresses than single-crystals
    c Poly-crystals with smaller grain sizes have higher yield stresses
    d All of the above

Deeper questions

The following questions require some thought and reaching the answer may require you to think beyond the contents of this TLP.

  1. Explain why the intersection of two screw dislocations is important to work hardening.

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