It should be noted here that alloys are not general mixtures, and can even be pure, such as single-phase metal mutual compounds. The addition of alloying elements can form solid solutions, compounds, and produce endothermic or exothermic reactions, thus changing the properties of the metal matrix.
Alloys are often made to improve the properties of elemental elements, such as steel, which is stronger than its main constituent, iron. The physical properties of alloys such as density, reactivity, young's modulus, conductivity and thermal conductivity may be similar to those of the constituent elements of alloys, but the tensile strength and shear strength of alloys are usually quite different from the properties of the constituent elements. This is because the alloy is very different from the arrangement of atoms in a single substance.
A small amount of one element can make a big difference to the properties of the alloy. For example, impurities in ferromagnetic alloys can change the properties of alloys.