What is a Shockley partial dislocation?

Shockley partial dislocations generally refer to a pair of dislocations which can lead to the presence of stacking faults. This pair of partial dislocations can enable dislocation motion by allowing an alternate path for atomic motion.

Why Frank partial dislocation is called a sessile dislocation?

The Frank partial is an edge dislocation and since the Burgers vector is not contained in one of the {111} planes, it cannot glide and move conservatively under the action of an applied stress. Such a dislocation is said to be sessile, unlike the glissile Shockley partial.

What is sessile dislocation?

[′ses·əl ‚dis·lō′kā·shən] (metallurgy) A dislocation in a metal lattice that is relatively immobile, offering an obstacle to the movement of other dislocations.

What is a perfect dislocation?

The magnitude of Burgers vector b of a (perfect) dislocation is defined as the distance from a lattice point to the nearest lattice point. There may exist a meta-stable position for an atom given by a vector ｂ1 whose magnitude is smaller than b. The Burgers vector of the perfect dislocation can split to b = ｂ1+ｂ2.

What is the function of the Lomer Cottrell dislocation?

This is the Lomer–Cottrell dislocation. It is sessile and immobile in the slip plane, acting as a barrier against other dislocations in the plane. The trailing dislocations pile up behind the Lomer–Cottrell dislocation, and an ever greater force is required to push additional dislocations into the pile-up. ex. FCC lattice along {111} slip planes

How does the Lomer Cottrell junction affect the slip plane?

It is sessile and immobile in the slip plane, acting as a barrier against other dislocations in the plane. The trailing dislocations pile up behind the Lomer–Cottrell dislocation, and an ever greater force is required to push additional dislocations into the pile-up.

What are the benefits of Lomer Cottrell locks?

Recently Lomer-Cottrell (L-C) locks as barriers to pin and entrap dislocations and thus to enhance work-hardening and ductility of nanostructured (NS) metals and alloys have received attention.

How are the L-C Lock dislocations formed?

The new type of L-C locks were observed and identified using high resolution transmission electron microscopy in a NS 7075 Al alloy processed by high-pressure torsion (HPT). The L-C locks could be formed via reactions between Shockley dislocations enclosing the intersected SFs on different {111} slip planes during HPT.