Question

The primary strengthening mechanism in 70:30 brass is

• A. Precipitation hardening
• B. Dispersion strengthening
• C. Fiber strengthening
• D. Solid solution strengthening

Hint:

In substitutional alloys like brass, strengthening typically arises from solid solution hardening due to the atomic size mismatch and lattice distortion.

Answer 1

The Correct Option is D

70:30 brass is an alloy of copper and zinc with approximately 70% copper and 30% zinc. In such a binary alloy, the zinc atoms substitute for copper atoms in the crystal lattice, creating lattice distortions. These distortions hinder the motion of dislocations, which is a fundamental mechanism of plastic deformation. This interference with dislocation motion increases the yield strength and hardness of the alloy. This mechanism is termed solid solution strengthening, where the alloying element (zinc) is completely dissolved in the host metal (copper), and the resulting solid solution offers resistance to deformation. Other mechanisms like precipitation hardening, dispersion strengthening, and fiber strengthening do not apply to 70:30 brass.