Q1: In case of brasses, with decreasing zinc percentage and increasing copper percentage, its __________ increases.

ANS:A - percentage elongation

Certainly! Let's delve into each of these factors and how they are affected by the changes in zinc and copper percentages in brass alloys:

1. Percentage Elongation:
   • Percentage elongation is a measure of the ductility of a material, indicating its ability to undergo deformation before fracture.
   • Increasing the copper content in brass alloys tends to enhance ductility or elongation. Copper is known for its high ductility compared to zinc.
   • As the zinc percentage decreases and the copper percentage increases, the resulting brass alloy typically exhibits higher ductility, leading to an increase in percentage elongation. This means the material can stretch more before breaking.
2. Brinell Hardness:
   • Brinell hardness is a measure of a material's resistance to indentation or scratching.
   • Increasing the copper content in brass alloys generally results in increased hardness. Copper is harder than zinc.
   • As the copper percentage increases and the zinc percentage decreases, the resulting brass alloy tends to have higher hardness values, as copper contributes to greater strength and hardness.
3. Tensile Strength:
   • Tensile strength is the maximum stress a material can withstand before breaking under tension.
   • Similar to hardness, increasing the copper content in brass alloys typically leads to higher tensile strength. Copper contributes to greater strength and toughness compared to zinc.
   • Therefore, as the zinc percentage decreases and the copper percentage increases, the resulting brass alloy tends to exhibit higher tensile strength, as copper enhances the material's overall strength properties.

In summary, with decreasing zinc percentage and increasing copper percentage in brass alloys, the material generally becomes more ductile (higher percentage elongation), harder (higher Brinell hardness), and stronger (higher tensile strength). These changes are attributed to the differing mechanical properties of copper and zinc and their respective influences on the overall behavior of the brass alloy.