Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Void Formation and Evolution in Irradiated Metals Studied by Phase-Field Approach" By Rayaprolu Goutham Sreekar Annadanam Purdue MSE Preliminary Exam Advisor: Professor Anter El-Azab ABSTRACT The safe and efficient operation of nuclear reactors requires the structural materials to be stable chemically, microstructurally and dimensionally under energetic particle irradiation. An ubiquitous phenomenon that occurs in many structural alloys in nuclear reactors is volumetric swelling. This phenomenon is primarily attributed to the nucleation and growth of voids and bubbles filled with transmutation gases such as helium . Early attempts to model this phenomenon involved the use of the classical nucleation theory and reaction rate theory models to capture the nucleation and growth kinetics, respectively, and correlate the observed effects with the irradiation dose rate and temperature. However, these models suffered certain limitations associated with the requirement of homogeneity of the irradiated material and defect fields, and were thus not adequately reliable in explaining the experimental results and in making predictions. Relatively recently, the phase field approach was introduced with the goal to capture the concurrent nucleation and growth of voids and bubbles under the condition of dynamic point defect production by atomic collision cascades in irradiation environments. Of particular interest in this study are the phase field models for void nucleation and growth. In the literature, these models can be primarily classified into two types, those based upon Cahn-Hilliard type equations and others based upon combined Cahn-Hilliard and Allen-Cahn equations. While these models have been well tested, they are not able to provide quantitative predictions yet due to the yet-to-be completed theoretical underpinning of the phase field model parameters, especially the Allen-Cahn mobility. Such parameters require matching with the so-called sharp interface models, which represent the physics of void growth better. In addition to fixing the phase field model parameters, such a matching is also required to guarantee physical and thermodynamic consistency of the phase field approach. In this paper, I review the existing phase field models and discuss further steps to make the phase field consistent with sharp interface theory. Date: Thursday, November 21, 2019 Time: 8:00 A.M. Place: ARMS 1103