09. Crystal Defect - Line Defects WNP 2018-converted.pptx - Line Defects ENMT 603006 ENMT 613010 Wahyuaji NP Departemen Teknik Metalurgi dan Material

09. Crystal Defect - Line Defects WNP 2018-converted.pptx -...

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Line Defects ENMT 603006 / ENMT 613010 Wahyuaji NP Departemen Teknik Metalurgi dan Material FTUI Disclaimer: This lecture note is edited from different sources for the solely of teaching and learning purposes. It may contain copyrighted materials from their respective owners, therefore, apart from teaching and learning purposes, this lecture note should not be reproduced, stored, or transmitted in any form or by any means
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Consider a dislocation 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 Free surfaces, grain boundaries etc. Stress fields, strain fields, energy etc. E d , xx , yy , xy , xx , xy ... Interactions with other dislocations, interstitials, precipitates etc. Collective behaviour and effects of external constrains Long range interactions & collective behaviour & external constraints ** Static and dynamic effects and interactions should be included* * Dynamic effects include: (Altered) Stress field of a moving dislocation Interactions evolving in time Though these points are written as a sequence many of these have to be considered in parallel Note: the above step by step method may often not be the most practical one and there are techniques which take up collective behavio ur directly
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Slip Role of Dislocations Fracture Fatigue Creep Diffusion (Pipe) Structural Grain boundary (low angle) Incoherent Twin Semicoherent Interfaces Disc of vacancies ~ edge dislocation Crystal Growth (Screw dislocation) Note: Structural dislocations can also play a role in deformation and kinetic processes and more…!! Creep mechanisms in crystalline materials Dislocation climb Vacancy diffusion Cross-slip Grain boundary sliding
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Slip (Dislocation motion) Plastic Deformation in Crystalline Materials Twinning Phase Transformation Creep Mechanisms Grain boundary sliding
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