Aluminium alloys — identify the trade name by composition Which aluminium alloy is produced by melting aluminium with about 2 to 10% magnesium and roughly 1.75% copper? Select the commonly used trade name for this composition.

Introduction / Context:
Nomenclature of aluminium alloys in shop-floor and exam problems often uses trade names that hint at the main alloying elements and intended properties. Being able to map approximate compositions to these conventional names is a basic but important metallurgical skill for materials selection and heat-treatment planning.

Given Data / Assumptions:

• Base metal: aluminium.
• Alloying additions: magnesium in the range 2–10% and copper about 1.75% by mass.
• We are choosing among typical historical trade names used in manufacturing and textbooks.

Concept / Approach:
Magnalium is the long-established name for aluminium–magnesium alloys, typically with magnesium content anywhere from a few percent up to double digits, sometimes with minor copper, silicon, or nickel to tune strength and castability. Duralumin denotes aluminium–copper wrought alloys around 4% Cu with small Mg and Mn, optimized for age hardening. Y-alloy is an aluminium–copper–nickel–magnesium casting alloy for elevated temperature. Hindalium is a regional trade name for Al–Mg–Mn sheet alloys but not the classic Al–Mg with a defined copper addition near 1.75%.

Step-by-Step Solution:

Verification / Alternative check:
Property sets for magnalium emphasize low density and improved strength over pure aluminium plus good machinability; these align with Al–Mg systems containing minor Cu.

Why Other Options Are Wrong:

• Duralumin: primarily Al–Cu (~4% Cu) with lower Mg; the given Mg range is too large for classic duralumin.
• Y-alloy: requires notable nickel for hot strength.
• Hindalium: broadly Al–Mg–Mn sheet products; composition stated is not the canonical definition.
• Alclad: refers to metallurgical cladding, not alloy chemistry.

Common Pitfalls:
Assuming any Cu presence implies duralumin; conflating processing terms (alclad) with alloy names.

Final Answer: