Factors Influencing the Stability of Nickel-Base High-Temperature Alloys

The stability of nickel-base high-temperature alloys at elevated temperature is discussed in relation to structural changes which can occur under certain conditions liable to occur in service. Particular attention is given to associated effects on mechanical properties. The influence of composition and heat treatment, on formation and growth of phases in iron-rich nickel alloys and iron-free high-strength wrought and cast nickel-base alloys are reviewed, on the basis of research carried out to develop improved alloys of the respective types. Attention is drawn to precautions which may be taken in selection and control of composition and heat treatment, to achieve maximum stability of properties. It is u:ged that the nature of individual types of structural instability, and their respective effects on properties, should be adequately evaluated before restricting the use of alloys for specific applications. E.G.Richards is Leader of the Non-Ferrous Metals Research Group and R.M.Cook is Assistant to the Laboratory Manager at the Development and Research Department Laboratory of International Nickel Limited, Birmingham, England.