What is primarily added to the base metal to create an alloy?

Alloys are created by combining a base metal with additional elements, which significantly change the properties of the original metal. The primary purpose of adding other metals or elements is to enhance specific characteristics such as strength, corrosion resistance, ductility, and conductivity.

For example, steel is an alloy primarily made from iron and carbon. However, various other elements, like chromium in stainless steel or nickel in specialized steels, can be included to modify the steel's properties for different applications. This versatility is what makes alloys particularly valuable in welding and manufacturing.

While other options such as heat, carbon, and oxide layers play roles in processes involving metals, they do not define the essence of creating an alloy. Heat is typically used in processes like welding and shaping metals rather than forming alloys. Carbon is indeed a common additive to some alloys, particularly steel, but it is just one of many possible additions and not the most encompassing answer to what creates an alloy. Oxide layers are often a concern in welding because they can hinder adhesion, but they do not contribute to the alloying process itself.