The physical metallurgy of superalloys and titanium alloys

Abstract

The microstructures which may be obtained in superalloys and titanium alloys as a function of alloy chemistry and heat treatment and the contributions of the various phases to tensile, creep, fatigue, and fracture strength are described. The ways in which thermomechanical forming processes can affect the microstructures and hence influence the nature of subsequent heat-treatment processes in achieving improved properties are discussed. The physical metallurgy of the superalloys is summarized, particular attention being given to the various precipitation strengthening mechanisms available and the ways in which microstructures with the desired fatigue and creep properties can be achieved by heat treatment and control of alloy chemistry. The effects of processing on the microstructure and properties of the superalloys are reviewed, emphasis being given to the more recent thermomechanical processing techniques. The physical metallurgy of titanium alloys and the problems of achieving useful precipitation strengthening in both the α and β phases are discussed and the effects of thermomechanical processing on the microstructure. and properties of titanium alloys are reviewed.