A materials scientist is designing a ternary alloy composed of nickel (Ni)
CHEMISTRY · Multi-part · CBSE · Chemistry · Metals and Non-metals · Metals and Non-metals
Problem
A materials scientist is designing a ternary alloy composed of nickel (Ni), chromium (Cr), and carbon (C). Chromium atoms will substitute for nickel atoms, while carbon atoms will occupy interstitial sites within the same lattice.
The target composition is 70% Ni, 25% Cr, and 5% C by atom.
(1) Part 1: (a) Sketch a single cubic unit cell that simultaneously includes both substitutional Cr and interstitial C in appropriate proportions to approximate the target composition. Distinguish the three atom types with unique symbols or shading and label the unit-cell edges.
(2) Part 2: (b) Show how the positions of Cr atoms in your sketch preserve overall lattice symmetry, and justify any deviations you introduce to accommodate the interstitial carbon.
(3) Part 3: (c) Predict qualitatively how the combined presence of Cr and C will influence the alloy’s tensile strength relative to pure Ni. Support your prediction with specific structural arguments derived from your particle-level representation.
(4) Part 4: (d) Identify one processing challenge that might arise when cooling this alloy from the melt, and propose a microscopic explanation rooted in the arrangement you have drawn.