Browsing by Author "Newell, Andrew Phifer"

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    Microstructure Studies of Ti-6Al-4V Near-Net Shape Structural Components as Prepared by the Arcam Electron Beam Melting Process
    (2009-07-09) Newell, Andrew Phifer; J. Michael Rigsbee, Committee Chair; Jerome J. Cuomo, Committee Co-Chair; John M. Mackenzie, Committee Member
    The Arcam electron beam melting (EBM) process is used for rapid prototyping of fully functional metallic parts. Arcam uses electron beam scanning technology similar to a scanning electron microscope to form near-net shape components by selectively melting consecutive finite layers of alloy powder according a 3-D computer-aided design (CAD) file. The Arcam EBM process is being considered as a technology that can produce out-of-production Ti-6Al-4V alloy components for aging aircraft. Two Arcam EBM machines are currently in use at NC state university; the Arcam S12 and the Arcam A2. The microstructures of three samples from preliminary production runswere characterized by optical, scanning electron (SEM), transmission electron (TEM), and scanning transmission electron microscopy (STEM). The microstructures of this limited sample set of as-built solid objects generally consisted of Widmanstatten morphologies of fine acicular alpha laths with retained beta between the alpha phase. Prior beta grain size and volume fraction of retained beta were determined by quantitative metallography. Porosity was found in all samples from both machines due to non-optimization of the processing parameters.