PREDICTING THE SIZE-AND TEMPERATURE-DEPENDENT SHAPES OF PRECIPITATES IN Al-Zn ALLOYS

摘要

We study theoretically the size versus shape versus temperature relation of precipitates in Al-Zn via quantum-mechanical first-principles simulations. Our parameter-free model, based on a mixed-space clus- ter expansion, allows the prediction of the experimentally observed size and temperature dependences of the precipitate shape. We find that aging experiments can be explained in terms of equilibrium shapes. The precipitates change from a nearly spherical to a more ellipsoidal/hexagonal shape with increasing size and decreasing temperature.