High-carbon steel displays a markedly greater yield strength than pure iron
CHEMISTRY · Single correct · GCSE · Chemistry · Bonding, Structure and the Properties of Matter · Bonding, Structure and the Properties of Matter
Problem
High-carbon steel displays a markedly greater yield strength than pure iron. Which of the following best explains this observation?
(a) Carbon atoms substitute for iron atoms, leaving vacant lattice sites that make the crystal harder to tear apart.
(b) Carbon atoms form strong covalent Fe–C bonds that rigidly lock neighbouring iron atoms together, so the lattice cannot slip.
(c) Smaller carbon atoms occupy the interstitial sites in the iron lattice, producing lattice strain that pins dislocations and thus raises the stress required for plastic deformation.
(d) By decreasing the spacing between iron atoms, carbon increases the density of metallic bonding electrons, making the lattice resist deformation.