In amalgam alloy, which element reduces gamma-2 and decreases creep and corrosion, increasing strength?

In amalgam alloy, which element reduces gamma-2 and decreases creep and corrosion, increasing strength?

• A. Silver
• B. Tin
• C. Copper
• D. Zinc

Answer: (C)

The key idea is that the weaker, corrosion-prone phase in dental amalgam is the gamma-2 phase, which is tin-mercury. Reducing this phase makes the material much more resistant to creep under chewing loads and to corrosion, so it becomes stronger and more durable. Copper does this by forming copper-tin intermetallics that replace or suppress the gamma-2 phase in the set amalgam. With gamma-2 diminished, the alloy relies more on the tougher gamma-1 (silver-mercury) portions and copper-tin compounds, boosting strength and longevity. Silver is already tied to the stronger gamma-1 phase, tin is a component of gamma-2, and zinc serves mainly as a scavenger to reduce oxidation and moisture-related issues rather than altering gamma-2. Hence copper is the element that best achieves the described effect.

The key idea is that the weaker, corrosion-prone phase in dental amalgam is the gamma-2 phase, which is tin-mercury. Reducing this phase makes the material much more resistant to creep under chewing loads and to corrosion, so it becomes stronger and more durable. Copper does this by forming copper-tin intermetallics that replace or suppress the gamma-2 phase in the set amalgam. With gamma-2 diminished, the alloy relies more on the tougher gamma-1 (silver-mercury) portions and copper-tin compounds, boosting strength and longevity. Silver is already tied to the stronger gamma-1 phase, tin is a component of gamma-2, and zinc serves mainly as a scavenger to reduce oxidation and moisture-related issues rather than altering gamma-2. Hence copper is the element that best achieves the described effect.