Abstract
This work details the additive friction stir-deposition (AFS-D) of copper and evaluation of its microstructure evolution and hardness. During deposition, a surface oxide is formed on the deposit exterior. A very fine porosity is formed at the substrate–deposit interface. The deposit (four layers of 1 mm nominal height) is otherwise fully dense. The grains appear to have recrystallized throughout the deposit with varying levels of refinement. The prevalence of twinning was found to be dependent upon the grain size, with larger local grain sizes having a higher number of twins. Vickers hardness measurements reveal that the deposit is softer than the starting feedstock. This result indicates that grain refinement and/or higher twin densities do not replace work hardening contributions to strengthen Cu processed by additive friction stir-deposition.
Highlights
IntroductionThe additive approach builds a component by bonding (small) units of material, such as powder or metal sheets, together into a larger piece
Additive manufacturing is an effective method for the fabrication of prototypes and components for industrial use, enabling faster and more economical production of parts [1].The additive approach builds a component by bonding units of material, such as powder or metal sheets, together into a larger piece
The occurrence of this porosity is attributed to the lack of substrate surface preparation and/or the low initial deposition temperature, as the region of interest was deposited at the onset when the tool had not yet reached the steady-state deposition temperature
Summary
The additive approach builds a component by bonding (small) units of material, such as powder or metal sheets, together into a larger piece. By controlling where these small material units are bonded, a (near-)net shape geometry may be obtained. There are many different additive manufacturing technologies, with the most common of these using high energy beams, such as lasers, to induce material bonding [1]. Many metal additive manufacturing technologies are fusion-based and rely on melting and subsequent solidification of the feedstock material in order to achieve metallurgical bonding. Several limitations arise from the use of fusion-based approaches for additive manufacturing
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