The Annealing Induced Solid State Transformation of Quenched Beta Cr-Ti

Abstract

AbstractMicrostructural changes in the bcc-based water-quenched alloy β Cr40Ti60 have been investigated as a function of annealing time at 873 K. The as-quenched structure has been found to contain a non-ideal form of the ω structure, which has been detected and characterized on the basis of diffuse scattering to which it gives rise in electron diffraction patterns. Annealing at 873 K results initially in platelet precipitates of the metastable β″ phase, which is found to posses a bulk body centered tetragonal structure in which chemical ordering has been detected via electron diffraction and high resolution microscopy. After several hours of annealing at 873 K the equilibrium phases α-Ti and the C15 Laves phase Cr2Ti form as spherical polycrystalline aggregates. No evidence is found of reported annealing-induced amorphization [1]. It is suggested that amorphization cannot occur in this alloy via thermal activation, and that the reported findings may have resulted from impure specimens.