Aluminium alloy families — Y-alloy composition: Identify the composition range that correctly represents the classic Y-alloy (an Al–Cu–Ni–Mg high-temperature casting alloy).

Introduction / Context:
Y-alloy is a well-known aluminum casting alloy formulated for better strength retention at elevated temperatures (e.g., in some engine components). Recognizing its distinctive Ni-bearing composition differentiates it from duralumin and other Al–Cu–Mg wrought alloys used at lower temperatures.

Given Data / Assumptions:

• We seek a composition that includes copper and nickel with minor elements improving castability and strength at temperature.
• Ranges are approximate and typical of handbook values.
• Balance of the alloy is aluminum.

Concept / Approach:
Classic Y-alloy contains copper for precipitation strengthening and nickel to improve hot strength and creep resistance. Small additions of manganese, silicon, magnesium, and iron aid castability, strength, and control of intermetallics. Duralumin-like compositions lack nickel and are primarily wrought; tin-bearing options relate to bearing alloys, not Y-alloy.

Step-by-Step Solution:
Identify the signature element: nickel at about 1.8 to 2.3% is characteristic of Y-alloy.Confirm supporting elements: copper ~3.5 to 4.5%, manganese ~1.2 to 1.7%, with small silicon, magnesium, and iron additions.Match the listed range to these features.Select option (b) as the correct Y-alloy composition.

Verification / Alternative check:
Handbooks categorize Y-alloy among Al–Cu–Ni–Mg casting alloys with good strength at moderately elevated temperatures.

Why Other Options Are Wrong:
Option (a) corresponds to duralumin-type wrought alloy (no nickel).

Option (c) is magnesium-rich and does not represent Y-alloy.

Option (d) is a tin–copper bearing alloy family, not Y-alloy.

Option (e) resembles a low-alloy Al–Zn–Mg composition, not Y-alloy.

Common Pitfalls:
Confusing wrought duralumin with cast Y-alloy; overlooking the critical role of nickel in Y-alloy for high-temperature performance.

Final Answer:
3.5 to 4.5% copper, 1.2 to 1.7% manganese, 1.8 to 2.3% nickel, 0.6% each of silicon, magnesium and iron, balance aluminium