An alloy containing approximately 56% Ni and 17% Mo (balance Cr and others) is commercially known as which corrosion-resistant material?

Difficulty: Easy

Correct Answer: Hastelloy C

Explanation:

Introduction / Context:Material selection in corrosive chemical environments often involves nickel-based alloys. Recognizing signature compositions helps quickly identify candidates for acids, chlorides, and reducing media.

Given Data / Assumptions:

  • Typical composition near: Ni ~56%, Mo ~16–17%, Cr ~15–16% (Hastelloy C family).
  • Service: strong corrosion resistance, especially in chlorides and mixed acids.

Concept / Approach:Hastelloy C-type alloys (e.g., C-276) are Ni–Mo–Cr systems optimized for broad corrosion resistance. Monel is Ni–Cu; Inconel is Ni–Cr–Fe (high-temperature oxidation resistance); bronzes are Cu-based; Nichrome is Ni–Cr heating alloy. The given Ni–Mo signature points to Hastelloy C.

Step-by-Step Solution:1) Match high nickel and molybdenum content to alloy families.2) Exclude Ni–Cu (Monel) and Ni–Cr–Fe (Inconel) based on Mo content.3) Select Hastelloy C as the correct commercial name.

Verification / Alternative check:Supplier datasheets list Hastelloy C-276: Ni ~57%, Mo ~16%, Cr ~16%, confirming the characteristic composition and application domain.

Why Other Options Are Wrong:Monel: lacks significant Mo; mainly Ni–Cu.Inconel: designed for high-temperature oxidation with Ni–Cr–Fe; Mo lower or absent depending on grade.Bronze: Cu-based, unrelated composition.Nichrome: Ni–Cr heating element alloy; no high Mo content.

Common Pitfalls:Confusing trade names among Ni-based families; always check key alloying elements to distinguish corrosion vs. high-temperature roles.

Final Answer:Hastelloy C

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