Decomposition of the Solid Solution the The All-Beta βIII

Abstract

The decomposition of the solid solution in the βIII alloy (Ti-11,5 Mo-6Zr-4,5 Sn) is of interest because various transformations occur inside: from diffusional transformations (α and isothermal ω phases) to displacive transformations (athermal ω phase). The decomposition has been studied by two main techniques:

• elastic modulus measurements by the resonant frequency method in the range 0,5 khz to 10 khz

• internal friction measurements in the cycle and kilocycle range from 10ºK to 600ºK

These techniques are interesting because the formation of the various phases leads to very important increases of modulus and to two anelastic phenomena (1) (2) (3) (4) a P₁ peak and a P₂ peak at about −170ºC and 250ºC at one cycle (5) (fig 1): the P₂ peak is associated with the instability of solid solution before the diffusional transformation β→w isothermal and the P₁ peak is associated with the instability of solid solution before the displacive transformation β→w athermal.