As we discussed in class the phases on a phase diagram are a

As we discussed in class, the phases on a phase diagram are assigned in the order
they were discovered. Primarily this would have been on the basis of changes in
properties. Reviewing the Fe-C phase diagram, there is no beta phase present. Can you
find out what happened to the beta phase? In ancient times, there would have been a
property change associated with a specific composition and temperature that would have
lead to the naming of it as a distinct phase. As modern characterization techniques
became available, it was discovered that there was no change in the composition or
structure at this temperature that was associated with the observed change in properties.
Why did beta get kicked off the Fe-C phase diagram?

Solution

Please refer below points for answer

1- Beta phase and alpha phase are having same crystal structure of iron.

2 - There are no paramagnetic properties in Beta phase due to the expanded lattice parameter.However alpha ferrite (-Fe) are having magnetic prperties.

3 - The primary phase of low-carbon or mild steel and most cast irons at room temperature is ferromagnetic ferrite (-Fe). As iron or ferritic steel is heated above the critical temperature A2 or Curie temperature of 771 °C (1044K or 1420 °F),the random thermal agitation of the atoms exceeds the oriented magnetic moment of the unpaired electron spins in the 3d shell.

4- Beta ferrite is crystallographically identical to alpha ferrite, except for magnetic domains and the expanded body-centered cubic lattice parameter as a function of temperature, and is therefore of only minor importance in steel heat treating.

5- For this reason, the beta \"phase\" is not usually considered a distinct phase but merely the high-temperature end of the alpha phase field.