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Difficulty: MediumAlloys: Classification, Compositions, Physical Properties, and Uses

Duralumin, an alloy primarily composed of aluminium along with copper, magnesium, and manganese, exhibits higher tensile strength than pure aluminium because the presence of atoms of different sizes distorts the metallic lattice and hinders the slipping of crystal planes.

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Answer

The statement is True. Duralumin consists of aluminium alloyed with copper, magnesium, and manganese. The introduction of atoms of different sizes distorts the regular metallic lattice of aluminium, which impedes the movement of atomic planes and increases overall tensile strength.
The statement is true because Duralumin is formed by alloying aluminium with copper, magnesium, and manganese. The differing atomic sizes of these constituent elements cause structural lattice distortion, which prevents atomic layers from sliding easily past each other and enhances tensile strength.

Step-by-Step Solution

1
Verify the elemental composition of Duralumin.
Duralumin is an aluminium-based alloy containing approximately 94% aluminium, 4% copper, 1% magnesium, and 0.5-1% manganese.
Confirming the constituent metals verifies the composition stated in the stem.
2
Analyze the structural effect of alloying on the metallic crystal lattice.
Copper, magnesium, and manganese atoms have different atomic sizes compared to aluminium atoms, causing localized distortion in the metallic lattice.
Disrupting the uniform arrangement of identical host atoms alters the physical behavior of the metal matrix.
3
Relate lattice distortion to mechanical property modifications (tensile strength).
Lattice distortion creates stress fields that impede the movement of dislocations and slipping of crystal layers under applied force, resulting in higher tensile strength.
Interference with layer sliding directly explains why alloys are stronger and harder than their pure constituent metals.

Key Concept

Alloy composition and strengthening mechanism via lattice distortion
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Topics

Alloys: Classification, Compositions, Physical Properties, and Uses

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