What is polygonization?
polygonization (plural polygonizations) (mathematics) The subdivision of a plane into polygons. (metallurgy) The formation of subgrains within the grains of a metal when worked.
What is Polygonization in recovery?
The recovery of the cell structure typically leads to the formation of a subgrain structure in which the cell or subgrain walls are atomically sharp like regular grain boundaries albeit with smaller lattice misorientations, hence it is also known as polygonization.
What do you understand by annihilation of dislocation?
Annihilation. Each dislocation is associated with a strain field which contributes some small but finite amount to the materials stored energy. When the temperature is increased – typically below one-third of the absolute melting point – dislocations become mobile and are able to glide, cross-slip and climb.
What is dislocation density?
The dislocation density is a measure of the number of dislocations in a unit volume of a crystalline material. Two methods are used to measure this parameter. In the first, the total length of dislocation line in a unit volume is measured and divided by the volume to give rD = (L / 13) m-2.
What is the main purpose of annealing?
Annealing is a heat treatment process which alters the microstructure of a material to change its mechanical or electrical properties. Typically, in steels, annealing is used to reduce hardness, increase ductility and help eliminate internal stresses.
How is annealing process done?
In the case of ferrous metals, such as steel, annealing is performed by heating the material (generally until glowing) for a while and then slowly letting it cool to room temperature in still air. Copper, silver and brass can be either cooled slowly in air, or quickly by quenching in water.
Why a pair of dislocations would annihilate each other?
Dislocations on the same slip plane but of opposite sign can annihilate each other when they collide. Dislocations on different slip planes need to change planes before annihilation can occur. This process takes place by edge dislocation climb and screw dislocation cross slip.
What is recovery and recrystallization process?
Recovery – A low-temperature annealing heat treatment designed to eliminate residual stresses introduced during deformation without reducing the strength of the cold worked material. Recrystallization temperature – The temperature above which the effects of strain hardening are eliminated during annealing.
How are dislocations formed?
Dislocations are generated by deforming a crystalline material such as metals, which can cause them to initiate from surfaces, particularly at stress concentrations or within the material at defects and grain boundaries.
What is meant by annealing process?
Definition of process annealing : the process of softening steel by heating it to a temperature near but below the transformation range and then cooling slowly.
What is the process of polygonization of the matrix?
This includes heat treatment to produce polygonization in the matrix, a process of accumulation of dislocations into lower energy low-angle grain boundaries or tilt walls, see Fig. 9. Fig. 9. A schematic of a low-angle grain boundary or tilt wall.
Why is slip polygonization also called slip-polygonization?
Therefore, the DP is also called slip polygonization because the formation of walls consisting of dislocations does not involve diffusive dislocation climb, in contrast to the case of SP [101]. As a result, by DP, a dynamic polygon structure arises in the form of a periodic system of tilt walls of dislocations ( Figure 27.16 ).
How does dynamic polygonization occur during crystal bending?
During crystal bending by thermomechanical stress in the initial stage of plastic relaxation, the mechanism of dynamic polygonization (DP) begins, correlating with dislocation slip mode only (easy-glide stage). During DP, vertical walls of dislocations perpendicular to the dislocation slip plane are formed.
What is the transaction model of communication?
The transaction model of communication describes communication as a process in which communicators generate social realities within social, relational, and cultural contexts.