---
title: "Samples of pure iron, \\(\\text{Fe(s)}\\), and carbon steel (an interstitial alloy of iron and carbon) of identical dimensions are subjected to equal mechanical shear stress at \\(298\\text{ K}\\). Particulate-level representations of the crystal lattices of both materials are shown below. Which of the following best predicts the comparative mechanical response of the carbon steel and provides the correct particulate-level justification?"
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url: "https://nerd-notes.com/ubq/123486/"
date_modified: "2026-09-28T11:59:54+00:00"
---

# Samples of pure iron, \(\text{Fe(s)}\), and carbon steel (an interstitial alloy of iron and carbon) of identical dimensions are subjected to equal mechanical shear stress at \(298\text{ K}\). Particulate-level representations of the crystal lattices of both materials are shown below. Which of the following best predicts the comparative mechanical response of the carbon steel and provides the correct particulate-level justification?

Samples of pure iron, \(\text{Fe(s)}\), and carbon steel (an interstitial alloy of iron and carbon) of identical dimensions are subjected to equal mechanical shear stress at \(298\text{ K}\). Particulate-level representations of the crystal lattices of both materials are shown below. Which of the following best predicts the comparative mechanical response of the carbon steel and provides the correct particulate-level justification?

![Two square panels appear side by side in grayscale. A top legend defines: large open circle = \(\text{Fe}\) atom; small solid black circle = \(\text{C}\) atom. The left panel, labeled Pure \(\text{Fe}\), shows exactly 16 large open circles arranged in a uniform \(4 \times 4\) planar array with straight, unbent horizontal and vertical rows. The right panel, labeled Carbon Steel, shows exactly 16 large open circles arranged in four rows, with exactly 2 small solid black circles situated in the interstitial spaces between rows; the presence of the small solid black circles causes visible local displacement and curvature of the adjacent rows of large open circles. No other particles, labels, text, or annotations appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1790596794-GHGnYL.jpg)

- **A.** The carbon steel undergoes greater permanent deformation because the added carbon atoms contribute extra valence electrons, increasing the fluidity of the electron sea.
- **B.** The carbon steel undergoes less permanent deformation because the carbon atoms form localized, directional covalent network bonds that eliminate the metallic character of the lattice.
- **C.** The carbon steel undergoes less permanent deformation because the interstitial carbon atoms distort the regular lattice, restricting the layers of iron atoms from sliding past one another.
- **D.** The carbon steel undergoes greater permanent deformation because the interstitial carbon atoms push the iron atoms farther apart, weakening the metallic bonding throughout the solid.

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