Prediction of atomic configurations in alloys

Abstract

Improvements in the description of configurational thermodynamics have enabled appropriate evaluations of atomic configurations in the ordered and disordered phases. From the cluster variation method (CVM) calculations, the substitution behaviors of the third element in Ti 3Al and TiAl intermetallic compounds are in good agreement with those evaluated by ALCHEMI and X-ray diffraction. The equilibrium concentrations of solute elements and atomic pairs in the ferrite matrix were estimated by thermodynamic calculations with the sublattice model (Thermo-calc.) and CAM, respectively. A good correlation is observed between the long term creep strength of carbon steels at 773 K and 88 MPa and the concentrations of Mn–C and Mo–C atomic pairs, suggesting that the strength is controlled by these atomic pairs. In the case of Cr–Mo steels, however, the strengthening effect of M–C atomic pair is not observed at 823 K and 88 MPa, and the contribution of solute elements such as Cr, Mn and Mo in the ferrite matrix seems to be dominant.