Alloys are frequently used in structural engineering and manufacturing because they exhibit greater mechanical strength and hardness than pure metals. Which of the following structural factors best explains why introducing a secondary element increases the hardness of a metal?
- Atoms of differing sizes disrupt the regular crystal lattice, hindering the movement of atomic layers past one another.Answer
- BThe constituent elements undergo a chemical reaction to form rigid giant covalent networks throughout the solid.
- CDelocalized valence electrons are completely removed, converting the metallic lattice into an ionic crystal structure.
- DThe added atoms expand in volume to completely fill all interatomic spaces and stop thermal vibrations.
Answer
Atoms of differing sizes disrupt the regular crystal lattice, hindering the movement of atomic layers past one another.
In a pure metal, identical atoms form regular layers that slip over one another with relative ease. When a secondary element with a different atomic radius is introduced to form an alloy, the regular lattice arrangement is distorted. This disruption prevents atomic layers from sliding smoothly, significantly increasing the hardness and tensile strength of the alloy.
Step-by-Step Solution
Key Concept
Lattice distortion and mechanical strengthening of alloys
Estimated Time:45s