Therefore, nickel is an important addition element of copper-based alloys, silver-white, metallic shine, so it is called white copper. Copper and nickel can be infinitely soluble with each other, thus forming a continuous solid solution, i.e. a single-phase alloy regardless of the proportion of each other. When the content of nickel melts into red copper D200 and exceeds 16%, the brightness of the alloy becomes absolutely as white as silver. The higher the content of nickel, the whiter the color. However, when it blends with copper, only if the proportion of nickel content does not exceed 70%, the naked eye can see the yellow of copper. Moreover, the content of nickel in white copper is usually 25%.