Segregation Science

Segregation is not only a large field, it is also not easily ploughed. Since it is instrumental for wootz blades, I will devote several science modules and two special modules to this topic.
  1. Basics of Segregation.
    Topics covered are: 1. Some basics about segregations. 2. Phase diagrams, "macroscopic" segregation and the segregation coefficient. 3. The flow of energy and particle currents through the solid-liquid interface during freezing - and what it implies.
  2. Constitutional Supercooling and Interface Stability
    Topics covered are: 1. Non-equilibrium and how systems try to get back to equilibrium. Exploiting the difference between currents and current densities. 2. What is constitutional supercooling and calculations for a simple model. 3. Supercooling, interface stability and dendritic growth plus some remarks to convection in the melt.
  3. Supercooling and Microstructure.
    Topics covered are: 1 How supercooling plus segregation determines the microstructure of the forming solid. 2. A closer look at what happens when we cast an object. 3. Temperature gradient and interfaces velocity are the most important parameters for the microstructure.
  4. 4. Segregation at High and Ambient Temperatures
    Topics covered are: 1 What could happen during cooling. 2. A simple model for macrosegregation at high temperatures 3. Microsegregation at high temperatures. 4. What is left at room temperature and a simple way to look at the effects of diffusion. The importance of microsegregation for the nucleation of precipitates.
  5. Striations.
    Striations, an universal expression of microsegregation, are necessary for wootz steel patterns but not contained in the preceding modules. Examples are given and discussed.
Related modules are:
  1. Segregation and Striations in CZ Silicon.
    Showing that segregation can have major effects - even in almost perfect crystals with very small impurity concentrations - and that it occurs typically in the form of striations
  2. Microsegregation and "Current Burst" theory.
    Comparing self-organizing features of Si electrochemistry to self-organization features of liquid-solid interfaces, speculating that striations are expressions of stochastic events synchronized by nearest neighbor interactions.

With frame With frame as PDF

go to Glossary

go to 6.2.2 Solidification and the Art of Casting

go to Science of Welding Steel

go to The Verhoeven - Wadsworth Jousting Tournament

go to 11.5.2 Structure by Dendrites?

go to Segregation at Room Temperature

go to 10.4. Crucible Steel 10.4.1 The Making of Crucible Steel in Antiquity

go to Segregation in Silicon

go to Powder Metallurgy

go to 1. Basics of Segregation

go to Constitutional Supercooling

go to Segregation at Room Temperature

go to Microsegregation and "Current Burst" Theory

go to Constitutional Supercooling and Interface Stability

go to TTT Diagrams 4. Experimental Construction of TTT and Phase Diagrams

© H. Föll (Iron, Steel and Swords script)