Curie Temperature

THE CURIE POINT OF IRON
At 770°C (1043 K), called the Curie temperature, iron loses its ferromagnetism.
That means:
Below 770°C → Iron is strongly magnetic
Above 770°C → Iron suddenly becomes non-magnetic

Why Does This Happen?

• Inside iron, tiny regions called magnetic domains are normally aligned.

• At lower temperatures → domains stay ordered

• As temperature rises → atomic vibrations increase

• At 770°C → thermal energy disrupts alignment

• The magnetic order collapses. Iron doesn’t lose its magnetic atoms it just loses the organised alignment.
  
  

What Iron Becomes Above Curie Point Above 770°C:

• Iron becomes paramagnetic

• It still responds slightly to a magnetic field

• But it won’t stick to a magnet on its own

• If you cool it back below 770°C, magnetism returns.

• 770°C is not melting point.

• Curie point → magnetic change

• Melting point of iron → about 1538°C

• So at 770°C, iron is still solid — just not magnetic.
  
  

Real-World Example
If you heat a nail with a blowtorch:
A magnet will stick at first
As it glows red hot → magnet suddenly falls off
That moment is the Curie temperature.