PREDICTING CHROMIUM DEPLETION OF NICKEL BASE ALLOYS

摘要

There are two so-called grain boundary chromium concentrations: the grain boundary chromium concentration at carbide free grain boundary sections and the interfacial chromium concentration at the interface between carbides and the matrix. Existing models for predicting grain boundary chromium depletion either predicts the former or the latter. A Monte Carlo based precipitation kinetics simulation approach has been developed to simulate the evolution of both the grain boundary and interfacial chromium concentration. Application of the method to Alloy 690 yields good agreement with experimental observations with regard to both the chromium depletion evolution and carbide precipitation kinetics. The effect of grain boundary character will also be discussed.