Damage-tolerant metallic composites via melt infiltration of additively manufactured preforms

Publication date: 5 August 2017
Source:Materials & Design, Volume 127
Author(s): Alexander E. Pawlowski, Zachary C. Cordero, Matthew R. French, Thomas R. Muth, J. Keith Carver, Ralph B. Dinwiddie, Amelia M. Elliott, Amit Shyam, Derek A. Splitter
AbstractA356/316L interpenetrating phase composites were fabricated by infiltrating additively manufactured 316L lattices with molten A356. Measurements of the thermal conductivity of the composites showed an inverse rule-of-mixtures dependence on the 316L volume fraction. Compression tests revealed that the stress-strain response of the composites can be tailored by adjusting both the volume fraction and the topology of the 316L reinforcement. Tension tests on composites with 39vol% 316L showed a strain to failure of 32%, representing an order of magnitude improvement over the strain to failure of monolithic A356. Inspection of the as-tested tensile specimens suggested that this exceptional damage tolerance is a result of the interpenetrating structure of the constituents. These results together demonstrate that this infiltration processing route avoids problems with intermetallic formation, cracking, and poor resolution that limit current fusion-based additive manufacturing techniques for printing metallic composites.

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