Question

What is the crystal structure of ϒ iron?

(a) Body-centered cubic

(b) Face-centered cubic

(c) Hexagonal closely packed

(d) Body-centered tetrahedral

I got this question in quiz.

This key question is from Iron-Carbon System and their Alloys in portion Constitution of Alloys and Phase Diagrams of Engineering Material & Metallurgy

Answer 1

Right option is (b) Face-centered cubic

To explain: Pure iron exists in three allotropic phases of α iron, ϒ iron, and δ iron. α iron and δ iron appear as body-centered cubic, whereas ϒ iron is a face-centered cubic that is stable between 908^oC and 1535^oC.