Hikari Corporation

Compared to ferrite, the gap between austenite atoms is wider.

* For details, see the Youtube video ↓

Basics of manufacturing Heat treatment ⑥ Equilibrium phase diagram ②

 

 

 

Let's calculate the size of the gap between the atoms of austenite, which is a face-centered cubic lattice.

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Cut out the face-centered cubic lattice on the orange side.

 

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* A ... Length of one side of body-centered cubic lattice r ... Atomic radius

 

From the figure

4r = √2a

 

Because the atomic radius of iron is 126pm

√2a = 4 × 126

A = 356.381pm

 

The

Anisotropy x is ...

x = a-2r

= 104.38pm

 

 

 

In this way, the gaps between the atoms of austenite, which is a face-centered cubic lattice, have an anisotropic shape.

At first glance, the atomic radius of carbon is 70 pm and the diameter is 140 pm, so it cannot enter the gap.

It seems that some of the iron atoms that make up austenite move and the carbon atoms can be dissolved.