The concept of materials with controlled microstructural architecture (MCMA) to
develop and fabricate structural materials with novel and possibly superior properties and
performance characteristics is a new paradigm or paradigm extension for materials science and
engineering. In the conventional materials science and engineering paradigm, structure
(microstructure), properties, processing, and performance features are linked in the development
of desirable materials properties and performance through processing methodologies which
manipulate microstructures. For many metal or alloy systems, thermomechanical treatment
combining controlled amounts of plastic deformation with heat treatment or aging cycles can
achieve improved mechanical properties beyond those attainable by conventional processing
alone (such as rolling or forging for example) through controlled microstructure development. In
this paper we illustrate a new concept involving the fabrication of microstructural architectures
by the process development and selective manipulation of these microstructures ideally defining
material design space. This allows for the additional or independent manipulation of material
properties by additive manufacturing (AM) using electron beam melting (EBM). Specifically we
demonstrate the novel development of a carbide (M23C6) architecture in the AM of a Co-base
alloy and an oxide (Cu2O) precipitate-dislocation architecture in the AM of an oxygen-containing Cu. While more conventional processing can produce various precipitate
microstructures in these materials, EBM produces spatial arrays of precipitate columns or
columnar-like features often oriented in the build direction. These microstructural architectures
are observed by optical microscopy and scanning and transmission electron microscopy.
Prospects for EBM architecture development in precipitation-hardenable Al alloys is also
discussed. In the EBM build process using precursor powders, the electron beam parameters
(including beam focus, scan speed and sequencing) produce localized, requisite thermodynamic
regimes which create or organize the precipitate-related spatial arrays. This feature demonstrates
the utility of AM not only in the fabrication of complex components, but also prospects for
selective property design using CAD for MCMA development: a new or extended processing-microstructure-property-performance paradigm for materials science and engineering in
advanced manufacturing involving solid free-form fabrication (SFF).Mechanical Engineerin
