Alloys are useful because they often have physical, mechanical and chemical properties that are different from their components, as Dr. Mats Hillert explains on Eurometaux. They represent a wide range of engineering materials that provide a variety of products with useful properties. Their properties can be changed through heat treatment and mechanical working.
Dr. Hillert further explains that an alloy’s properties are largely influenced by the method of the formation and treatment of the alloy. Typically, an alloy is more chemically stable than the elements it contains. Alloys are designed to have particular resistance to stresses, such as wear, corrosion, temperature and fatigue. Some are created to impart electrical or magnetic properties, formability and strength. Stainless steel alloys result from the combination of nickel, iron and chromium with other elements. They are specifically resistant to corrosion, unlike ordinary steel. Other examples of alloys are beryllium-copper alloys, which are stronger and possess higher electrical conductivity than other copper alloys.
The atoms of the elements in alloys have different sizes, placing them into different arrangements. This makes alloys harder than pure metal. There are also smart alloys that have unusual properties. An example is nitinol, a combination of nickel and titanium that returns to its original shape when heated or when an electric current is passed through it.