Analyzes the extensive experimental and theoretical results on the phase composition, structure and properties of aluminium alloys containing scandium. The text studies the effects of scadium on these properties from a physico-chemical viewpoint. The authors present binary, ternary and more complex phase diagrams for these alloys and consider in detail recrystallization, superplastic behaviour and decomposition of supersaturated solid solutions and the effects of solidification conditions on phase equilibria. The microstructure stability for aluminium alloys containing scandium is estimated, based on a quantitative analysis of the alloys structure and properties. The realtion between the structure and properties of alloys with differing phase compositions, and tha acting hardening mechanisms are discussed. The authors also give some practical recommendations for alloying aluminium alloys with scandium. The experimental results presented in this book have provided a basis for the development of commercial aluminium alloys for a wide range of industrial applications.