Ch 5 - deformations Flashcards
Explains the discrepancy between the theoretical and practical stress of a material
dislocation
deformation of ductile materials when a dislocation moves through a material; one dimensional
line defect
The type of deformation line defect produces
plastic deformation
the behavior in which a material experiences stress and can return to its original state
elastic deformation
the behavior in which a material experiences stress and is permanently deformed from the experience stress
plastic deformation
when are dislocations formed?
during solidification or when the material is deformed
What material properties do dislocations affect
mechanical, electronic, and photonic properties
Two basic types of dislocations
edge and screw
In burgers vector (b), what occurs when an edge deformation has and what variable does it mimic?
A closure failure occurs which makes burgers vector the same as the lattice constant (a)
Burgers vector is perpendicular to:
the edge dislocation line
An easy sign of edge dislocation
a half plane
The strength of the material depends on:
the force required to make the dislocation move
primary force to make dislocations move
shear
how is burger’s vector is parallel to what in an screw dislocation
screw dislocation line and perpendicular to the slip direction
Easy sign of a screw dislocation
no extra-half plane
Describe how ceramic is brittle?
The ions move together making it harder for dislocations to occur
two dimensional defect that deviates from perfect crystal packing
area defect
Why are external surfaces at higher energy?
They are not surround by all possible nearest neighbors; the atoms are tightly packed
are grain boundaries more chemically reactive?
Yes
What most materials are made up of? (crystal wise)
polycrystalline and made up of many single crystals
are the junction of grains grain boundaries?
Yes
What do high angle grain boundaries mean?
Significant misalignment
What do low angle grain boundaries indicate?
minor misalignment
special type of grain boundary across which there is a specific mirror lattice symmetry
a twin boundary
