What is defined as a metal that has one or more elements added, resulting in improved properties?

The term that describes a metal with one or more elements added to enhance its properties is alloy. Alloys are created to improve various characteristics such as strength, ductility, corrosion resistance, and melting point. The addition of different elements can result in significant changes to the physical and chemical properties of the base metal, making it more suited for specific applications.

In contrast, a compound refers to a substance formed when two or more elements are chemically bonded, resulting in properties that can differ significantly from those of the individual elements. Composite materials typically consist of two or more distinct materials, often with different physical or chemical properties, designed to optimize their combined performance. A blend might represent a mixture of materials but does not imply a uniform alteration of properties like an alloy does. Thus, the unique transformation that occurs when elements are added to create an alloy is what makes this term the correct choice in describing improved metallic properties.