  Additive manufacturing (AM) processes produce parts with improved physical,
chemical, and mechanical properties compared to conventional manufacturing
processes. In AM processes, intricate part geometries are produced from
multicomponent alloy powder, in a layer-by-layer fashion with multipass laser
melting, solidification, and solid-state phase transformations, in a shorter
manufacturing time, with minimal surface finishing, and at a reasonable cost.
However, there is an increasing need for post-processing of the manufactured
parts via, for example, stress relieving heat treatment and hot isostatic
pressing to achieve homogeneous microstructure and properties at all times.
Solidification in an AM process controls the size, shape, and distribution of
the grains, the growth morphology, the elemental segregation and precipitation,
the subsequent solid-state phase changes, and ultimately the material
properties. The critical issues in this process are linked with multiphysics
(such as fluid flow and diffusion of heat and mass) and multiscale (lengths,
times and temperature ranges) challenges that arise due to localized rapid
heating and cooling during AM processing. The alloy
chemistry-process-microstructure-property-performance correlation in this
process will be increasingly better understood through multiscale modeling and
simulation.
