Question

Which of the following statements is/are true about iron in iron-carbon equilibrium diagram?
A.It is soft and ductile
B.It is allotropic in nature
C.It is magnetic above curie temperature
D.Below the temperature if $1593^\circ C$, iron is in liquid state

Answer 1

Hint: The phase equilibrium diagram is a useful tool to visualize phase behavior. Phase equilibrium is a theoretical condition where the liquids and vapors have reached certain pressure and temperature conditions at which they can separate.

Complete step by step solution: This question may have more than one correct option.
The first option is that it is soft and ductile.
When iron is heated, at higher temperatures before iron melts, it is soft and ductile.
So the first option is correct.
Now we will check the next options.
The next option is that it is allotropic in nature.
During heating, as the temperature increases iron changes its allotropic forms from alpha iron \[\left( \alpha \right)\], known as ferrite to beta iron \[\left( \beta \right)\], gamma iron \[\left( \gamma \right)\] or austenite, then to delta iron \[\left( \delta \right)\]
So the second option is also correct.
The third option is that it is magnetic above curie temperature.
The Curie temperature (TC), or Curie point, is the temperature above which certain materials lose their permanent magnetic properties, which can (in most cases) be replaced by induced magnetism.
So above curie temperature iron will lose magnetic property.
So this option is incorrect.
The melting point of iron is $1593^\circ C$ . Below this temperature iron will be in solid state. So the fourth option is also incorrect.

So the correct option is A, B.

Note: Iron is an enigma – it rusts easily, yet it is the most important of all metals. 90% of all metal that is refined today is iron. Most is used to manufacture steel, used in civil engineering (reinforced concrete, girders etc.) and in manufacturing.