Question

What is the line QR in this fooling curve known as?

(a) Latent heating line

(b) Eutectic compound system

(c) Binary solid

(d) Horizontal thermal arrest

This question was addressed to me in an online interview.

I need to ask this question from Phases and Phase Diagrams topic in chapter Constitution of Alloys and Phase Diagrams of Engineering Material & Metallurgy

Answer 1

Correct option is (d) Horizontal thermal arrest

To elaborate: Cooling curves are obtained by plotting the measured temperatures at equal intervals during the cooling period of a melt to a solid. This diagram shows the cooling curve for a pure metal or compound. PQ is a uniform curve, whereas QR is known as the horizontal thermal arrest.