ME 487
FDISLOCATIONS AND THE MECHANICAL BEHAVIOR OF MATERIALS

Course Description

Imperfections in crystalline solids. Planar, line and point defects in solids. Emphasis will be placed on vacancies and dislocations. The static and dynamic features of dislocations will be discussed. Discussions on role of imperfections on materials behavior and development will be included.

Topics

• Introduction, defects in crystals, dislocation geometry, Burgers vectors, Burgers circuit, dislocation branching
• Slip, slip planes, Peierls-Nabarro stress, crystallography of dislocations, slip systems, cross slip, climb
• Prismatic loops, resolved shear stress, Dislocation mechanics: elasticity, force on dislocations, stress fields
• Dislocation mechanics: energy of dislocations, Frank’s rule, line tension, forces between dislocations, image forces
• Partial dislocations for FCC, HCP
• Partial dislocations for BCC, super dislocations, Dislocation interactions: jogs, kinks, jog motion
• Dislocation interactions: long jogs, prismatic loops, extended dislocations and jogs, dislocation forces, Dislocation nucleation
• Dislocation multiplication, arrays, low angle boundaries (LABs), tilt boundaries, twist boundaries, general LABs
• Frank’s relation, Stress fields and strain energy of dislocation arrays
• Strengthening mechanisms

Learning Outcomes

The student, upon completion of this course, will be able to:

• Determine the Burgers vector's, slip planes, and slip directions for perfect dislocations in common metal crystal structures.
  
• Determine the response of dislocations to applied stress.
  
• Compute the forces between dislocations to predict preferred dislocation motion and preferred dislocation arrangements.
  
• Apply Frank's rule to determine favorable dislocation reactions.
  
• Correctly identify the results of interactions between dislocations.