Hume-Rothery, William (1899–1968)

English metallurgist who studied the constitution of alloys. He established that the microstructure of an alloy depends on the different sizes of the component atoms, the valency electron concentration, and electrochemical differences.

Hume-Rothery was born in Worcester Park, Surrey, and educated at Oxford and the Royal School of Mines. His research was carried out at Oxford but financed by outside organizations such as the Armourers and Braziers Company, and he did not gain a formal university post until 1938. During World War II he supervised many government contracts for work on complex aluminium and magnesium alloys. He was appointed to the first chair of metallurgy in 1958.

With atoms of widely different sizes, at least two types of crystal lattice may form, one rich in one metal and one rich in the other. The presence of two types of structure can increase the strength of an alloy. This is why some brasses are much stronger than their component metals zinc and copper.

If the two elements differ considerably in electronegativity, a definite chemical compound is formed. Thus steel, an ‘alloy’ of iron and carbon, contains various iron carbides. Hume-Rothery and his team constructed the equilibrium diagrams for a great number of alloy systems.