The proposed cyclic heat treatment turned out to be an efficient way of grain refinement of the Ti–48Al–2Cr–2Nb alloy with a coarse-grained, lamellar initial microstructure. The biggest grain refinement effect, in the form of over an 8-fold reduction in the average equivalent diameter of plane sections, was obtained after 5 cycles of the treatment, which was a combination of continuous heating up to 1400 °C at 35 Ks− 1 followed immediately by cooling at 10 Ks− 1.
The most important parameters of the cyclic heat treatment having an influence on the grain refinement effect are the cycle temperature and the number of cycles within the range of 1 to 5. Incorrect selection of the treatment parameters results in lack of refinement, partial refinement or heterogeneity in grain sizes.
The full characteristics of the alloy grain refinement in the cyclic heat treatment processes, in particular when the refinement process only takes place partially or locally, requires that the value of the average grain diameter and standard deviation be specified and that distributions of the grain plane section area as a function of the frequency of occurrence and area fraction be presented.
The changes in the alloy microstructure observed in the cyclic heat treatment process point out the decisive role of undissolved lamellar precipitates of the γ phase in the process of forming the final grain size. The changes of microstructure obtained are reflected in changes of the mechanical properties of the alloy.