Additive Manufacturing (“3D printing”) technologies are attractive for their ability to produce near-net-shape parts in geometries that are difficult to obtain via traditional casting and subtractive machining. At the same time, additive materials are subject to extreme conditions that can include repeated thermal cycling both near and beyond the melting point and mechanical deformation due to powder densification and compliance to a (cold) build plate. These processes give rise to material microstructures quite unlike wrought materials and that harbor substantial micro- and macro-scale residual stresses. The ultimate properties, such as strength, toughness, corrosion resistance, and fatigue life are difficult to predict and can thus be a challenge to design around. This project will focus on microstructural modeling approaches, including both conventional phase field, phase field crystal; and level set methods, to understand the evolution of phase distributions, grain sizes, texture, and residual stresses in both as-built and heat-treated materials. Model results will both be informed by and feed into parallel work in macroscale thermomechanical finite element modeling, CALPHAD-based thermodynamics, and crystal plasticity and to both powder-scale and atomic-scale simulations. Emphasis will be on integration of model predictions with the work of collaborators engaged in experimental studies of the additive process itself and in detailed characterization of the microstructures, residual stresses, and ultimate properties using synchrotron-based x-ray and cold neutron diffraction, electron and optical microscopy, and a variety of mechanical and electrochemical tests.

 

key words

Additive manufacturing; Residual stress; Phase field; Phase field crystal; CALPHAD; Solidification; phase transformation;

Citizenship:  Open to U.S. citizens

Level:  Open to Postdoctoral applicants