Question

Eutectic reaction for iron-carbon system occurs at

• A. \(650^\circ C\)
• B. \(780^\circ C\)
• C. \(570^\circ C\)
• D. \(1147^\circ C\)

Hint:

In the Fe-C system, eutectic reaction occurs at \(1147^\circ C\) and eutectoid reaction occurs at about \(727^\circ C\).

Answer 1

The Correct Option is D

In the iron-carbon phase diagram, different important reactions occur at different temperatures. The eutectic reaction is the reaction in which liquid transforms into two solid phases on cooling. For the iron-carbon system, the eutectic reaction is: \[ L \rightarrow \gamma + Fe_3C. \] Here: \[ L \] represents liquid phase, \[ \gamma \] represents austenite, and \[ Fe_3C \] represents cementite. This eutectic reaction occurs at: \[ 1147^\circ C. \] The eutectic composition is approximately: \[ 4.3\%\ C. \] Therefore, the eutectic reaction for iron-carbon system occurs at: \[ 1147^\circ C. \]