Alloys Based on Orthorhombic Intermetallic Ti2AlNb: Phase Composition, Alloying, Structure, Properties

The article analyses data for chemical composition, manufacturing and processing methods for promising heat-resistant alloys based upon orthorhombic titanium intermetallic Ti2AlNb (O-alloys) developed within Russia and abroad. Phase diagrams typical for alloys based upon Ti-Al-Nb and general data for the phases formed in these alloys are provided. Concepts of aluminum and niobium equivalents used for multicomponent alloys are considered. The effect of alloying elements on a combination of mechanical properties of O-alloys, alloying principles, and compositions of the alloys developed are summarized. Characteristics of phase transformations occurring within alloys during heat treatment, including continuous heating and isothermal treatment, are provided. Typical microstructures of the alloys are presented; processing methods for their production and the influence of structural parameters on a combination of properties are described. Methods for manufacturing and processing routes of O-alloys are presented, which provide a good set of properties at room and elevated temperatures, as well as possible operating temperatures for refractory use.