1 / 15

530.352 Materials Selection

530.352 Materials Selection. Lecture #16: Dislocations Tuesday October 18 th , 2005. U. ~ 2  Th. E. F.  Th. r o. 1.25r o. r. Theoretical strength :. 2  Th = E  = E  L/L o 2  Th = E 0.25r o /r o = E/4  Th = E/8. Atomic description of plasticity:.

leann
Télécharger la présentation

530.352 Materials Selection

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 530.352 Materials Selection Lecture #16: DislocationsTuesday October 18th, 2005

  2. U ~ 2Th E F Th ro 1.25ro r Theoretical strength : . 2Th = E= E L/Lo 2Th = E 0.25ro/ro = E/4 Th = E/8

  3. Atomic description of plasticity:

  4. Slip easier with defects Hard to pull all at once x Much easier

  5. Defects in crystals • 0 - D • vacancies • 1-D • dislocation lines • 2-D • fault planes • grain boundaries

  6. Dislocation is the boundary between slipped and unslipped regions.

  7. Edge dislocations

  8. Burger’s Circuit • Start with atom “S”. • Count 4 to the right. • Count 4 down. • Count 4 to the left. • Count 4 up. • Finish with atom “F” • b connects S with F RHSF convention : Burger’s vector (b) S F

  9. t b Geometry of Edges Note: b is perpendicular to t t x b -> extra half plane

  10. Motion of Edges   t |b| b 

  11. Motion of Edges  t |b| b 

  12. Screw dislocations

  13. F S Burger’s Vector of Screws Note: b is parallel to t

  14. Motion of Screws

  15. Motion of Screws

More Related