Abstract
Powder-blown laser additive manufacturing adds flexibility, in terms of locally varying powder materials, to the ability of building components with complex geometry. Although the process is promising, porosity is common in a built component, hence decreasing fatigue life and mechanical strength. The understanding of the physical phenomena during the interaction of a laser beam and powder-blown deposition is limited and requires in-situ monitoring to capture the influences of process parameters on powder flow, absorptivity of laser energy into the substrate, melt pool dynamics and porosity formation. This study introduces a piezo-driven powder deposition system that allows for imaging of individual powder particles that flow into a scanning melt pool. Here, in-situ high-speed X-ray imaging of the powder-blown additive manufacturing process of Ti-6Al-4V powder particles is the first of its kind and reveals how laser-matter interaction influences powder flow and porosity formation.
Highlights
Additive manufacturing (AM) provides the opportunity to investigate every aspect of process-structure-properties relationships[1,2,3] and build structurally-optimized[4,5], complex[6], and functionally-graded components[7,8,9]
The powder-blown additive manufacturing process, or directed energy deposition (DED), is characterized by the interaction of a heat source with powder particles that flow from a nozzle into a melt pool[2]
In comparison to powder bed systems, DED undergoes different heat transfer mechanisms with more directional solidification as building an additional layer does not depend on the time it would take to spread a new layer of un-melted particles[2]
Summary
Additive manufacturing (AM) provides the opportunity to investigate every aspect of process-structure-properties relationships[1,2,3] and build structurally-optimized[4,5], complex[6], and functionally-graded components[7,8,9]. This study uses the high-resolution, time-resolved X-ray imaging technique at the Advanced Photon Source to evaluate the interactions between the laser beam, flying particles, and the melt pool behavior during rapid solidification in DED. By expanding this advanced monitoring technique to AM processes, researchers can take advantage of the fundamental physics of particle flow, fluid flow and heat transfer to take AM into a revolutionary means for scalable operations with flexible and functional materials
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