Chapter_5b_Crystal_Imperfections_dislocations - DISLOCATIONS Edge dislocation Part of Screw dislocation Dislocations in crystals Further reading

Chapter_5b_Crystal_Imperfections_dislocations -...

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DISLOCATIONS DISLOCATIONS Edge dislocation Screw dislocation Dislocations in crystals Introduction to Dislocations D. Hull and D.J. Bacon Pergamon Press, Oxford (1984) Recommended website Further reading Theory of Dislocations J. P. Hirth and J. Lothe McGraw-Hill, New York (1968) Advanced reading (comprehensive) MATERIALS SCIENCE MATERIALS SCIENCE & ENGINEERING ENGINEERING Anandh Subramaniam & Kantesh Balani Materials Science and Engineering (MSE) Indian Institute of Technology, Kanpur- 208016 Email: [email protected], URL: home.iitk.ac.in/~anandh AN INTRODUCTORY E-BOOK AN INTRODUCTORY E-BOOK Part of A Learner’s Guide A Learner’s Guide A Learner’s Guide A Learner’s Guide
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As seen before dislocations are 1D (line) defects The role of dislocations goes far beyond just ‘plasticity by slip’ They play an important role in a variety of deformation processes like creep , fatigue and fracture They can play a ‘ constructive role ’ in crystal growth They can provide short circuit paths for diffusion (pipe diffusion) Understanding the importance of dislocations in material behaviour cannot be overstated → hence it is very important to thoroughly understand the structure and behaviour of dislocations
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Consider a dislocation in in an infinite crystal Take into account finite crystal effects Consider interaction of dislocations with other defects Path to understanding the role of Dislocations in material behaviour Stress fields, strain fields, energy etc. Free surfaces, grain boundaries etc. , , , , , ... d xx yy xy xx xy E Interactions with other dislocations, interstitials, precipitates etc. Static and dynamic effects and interactions should be included* * Dynamic effects include: (Altered) Stress field of a moving dislocation Interactions evolving in time
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