Electron-beam additive manufacturing of high-temperature metals

Abstract

This article overviews electron-beam melting (EBM), including process optimization issues. Examples of EBM-fabricated components described include hexagonal close-packed Ti-6Al-4V, face-centered-cubic René 142 (a Ni-based superalloy), and body-centered-cubic pure iron, corresponding to a melt temperature range from 1375°C to 1630°C. Residual microstructures observed for these fabricated components by optical microscopy, scanning electron microscopy, and transmission electron microscopy include equilibrium as well as nonequilibrium features, which illustrate prospects for novel structure–property manipulation in the EBM process. The EBM process relies on available pre-alloyed, precursor powders that are selectively melted layer by layer by a computer-aided design scanned electron beam to form relatively small, but often complex, products or components. Direct metal deposition innovations capable of truly three-dimensional metal printing are described, especially high-temperature metals and alloys for future additive manufacturing technologies.