Zinc alloy is generally harder than copper. This is due to the fact that zinc alloys, such as brass, are composed of zinc and copper, with the addition of other elements to enhance properties like hardness. Copper, on the other hand, is a pure metal and does not have the same level of hardness as zinc alloys.

The hardness of a material is determined by its ability to resist indentation or scratching. According to the Brinell hardness test, which measures the depth of indentation made by a hard steel ball on the surface of a material, zinc alloys typically have a hardness ranging from 120 to 300 HB (Hardness Brinell), whereas copper has a hardness of around 70 to 150 HB. This indicates that zinc alloys are significantly harder than copper.

The addition of other elements to zinc alloys, such as tin, lead, and sometimes zinc itself, can further increase the hardness. For example, brass, a zinc-copper alloy, can have a hardness of up to 300 HB, which is much higher than the hardness of pure copper. The presence of these elements disrupts the crystal structure of the metal, making it more difficult for the atoms to move and thus increasing the material's resistance to deformation.

In summary, zinc alloys are generally harder than copper due to the presence of additional elements that enhance the material's hardness. This makes zinc alloys more suitable for applications where increased durability and resistance to wear are required.