Nickel–Chromium–Iron Alloys — Identifying Inconel Composition Which of the following nominal compositions most closely represents a classic Inconel (Ni–Cr–Fe) alloy grade?

Introduction / Context:
“Inconel” denotes a family of nickel-based alloys (notably Ni–Cr–Fe types like 600/601/625, etc.) used for high-temperature strength, oxidation resistance, and corrosion resistance. While exact compositions vary by grade, their hallmark is a high nickel base with significant chromium and some iron.

Given Data / Assumptions:

• We are comparing approximate, nominal compositions.
• Focus is on a representative Ni–Cr–Fe Inconel-type composition rather than Cu-bearing nickel alloys.
• Properties derive from solid-solution and, in some grades, precipitation strengthening.

Concept / Approach:
Classic Inconel Ni–Cr–Fe alloys typically contain ~70–76% Ni, ~14–17% Cr, and ~6–10% Fe (ranges depend on specific grade). Option (d) — 80% Ni, 14% Cr, 6% Fe — aligns closely with the Ni-rich, Cr- and Fe-containing profile of Inconel 600-type alloys. Option (b) is a Ni–Cu alloy (Monel family), not Inconel. Option (c) lacks iron and looks more like a binary Ni–Cr; option (a) has lower Ni and higher Fe than standard Inconel baselines.

Step-by-Step Solution:
Identify Inconel family: Ni–Cr–Fe foundation with high Ni content.Match each option to that pattern: (d) fits the canonical Ni–Cr–Fe ratios best.Eliminate non-matching chemistries: (b) is Monel-like; (c) lacks Fe; (a) is lower-Ni than typical Inconel grades.

Verification / Alternative check:
Manufacturer datasheets for Inconel 600 list Ni ~72 min, Cr 14–17, Fe 6–10, consistent with answer (d) in nominal terms.

Why Other Options Are Wrong:
(b) Represents Monel-type Ni–Cu alloy, not Inconel.(c) Omits iron; not representative of Ni–Cr–Fe Inconel grades.(a) Underrepresents nickel relative to typical Inconel compositions.

Common Pitfalls:
Assuming all nickel alloys with chromium are “Inconel”; composition families are distinct (Monel, Hastelloy, Inconel, etc.).

Final Answer:
80% nickel, 14% chromium and 6% iron