lecture9 - Lecture 09 Lecture 09 Dislocations &...

Info iconThis preview shows pages 1–13. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Lecture 09 Lecture 09 Dislocations & Strengthening Mechanisms Dislocations & Strengthening Mechanisms Chapter 7 - 1 islocations & Strengthening Mechanisms islocations & Strengthening Mechanisms Dislocations & Strengthening Mechanisms Dislocations & Strengthening Mechanisms ISSUES TO ADDRESS... ISSUES TO ADDRESS... • Why are dislocations observed primarily in metals • Why are dislocations observed primarily in metals and alloys? and alloys? • How are strength and dislocation motion related? • How are strength and dislocation motion related? • How do we increase strength? • How do we increase strength? • How can heating change strength and other properties? • How can heating change strength and other properties? Chapter 7 - 2 Mechanical Behavior & Structure Mechanical Behavior & Structure Controlled by Chemical bond Controlled by Processing via defects, crystal structure Chapter 7 - 3 “Chemistry” and microstricture Dislocations & Materials Classes Dislocations & Materials Classes • Metals: Disl. motion easier.-non-directional bonding + + + + + + + +-close-packed directions for slip. electron cloud ion cores + + + + + + + + + + + + + + + + • Covalent Ceramics (Si, diamond): Motion hard. irectional (angular) bonding-directional (angular) bonding • Ionic Ceramics (NaCl): Motion hard.-need to avoid ++ and - - neighbors. + + + + + + + + + + +---------- Chapter 7 - 4 Dislocation Motion Dislocation Motion Dislocations & plastic deformation • Cubic & hexagonal metals - plastic deformation by plastic shear or slip where one plane of atoms slides over adjacent plane by defect motion (dislocations). Chapter 7 - 5 • If dislocations don't move, deformation doesn't occur! Dislocation Motion (Cont’d) Dislocation Motion (Cont’d) Caterpillar… b Chapter 7 - 6 Dislocation Motion Dislocation Motion • Dislocation moves along slip plane in slip direction perpendicular to dislocation line • Slip direction same direction as Burgers vector Edge dislocation Screw dislocation Chapter 7 - 7 Comparison of Dislocation Motion Comparison of Dislocation Motion “Edge “Edge vs vs Screw Dislocations” Screw Dislocations” Chapter 7 - 8 Deformation Mechanisms Deformation Mechanisms Slip System – Slip plane- plane allowing easiest slippage • Wide interplanar spacings - highest planar densities – Slip direction- direction of movement - Highest linear densities – FCC Slip occurs on {111} planes (close-packed) in <110> directions (close-packed) => total of 12 slip systems in FCC Chapter 7 - 9 – in BCC & HCP other slip systems occur Deformation Mechanisms Deformation Mechanisms “Common Slip Systems” “Common Slip Systems” Chapter 7 - 10 Slip Systems in Common Metals Slip Systems in Common Metals After Dieter, echanical Metallurgy Mechanical Metallurgy (1990) Chapter 7 - 11 Stress and Dislocation Motion Stress and Dislocation Motion • Crystals slip due to a resolved shear stress, t R ....
View Full Document

This note was uploaded on 02/08/2011 for the course GENERAL EN 407 taught by Professor Akdogan during the Fall '10 term at Rutgers.

Page1 / 77

lecture9 - Lecture 09 Lecture 09 Dislocations &...

This preview shows document pages 1 - 13. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online