Selective Laser Melting of Metal Matrix Composites: FY18 Advanced Materials and Processes Line-Supported Program
MIT Lincoln Laboratory Lexington United States
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The capabilities of prototypes can be substantially enhanced by increasing the performance of the structural components that protect and support the payload. At MIT LL, the engineering of these components is particularly challenging because lead times are short, deformations in precision systems must be minimal, and prototypes face a range of environments, ranging from high shock and vibration loads during deployment to extreme and variable temperatures during operation. Structural performance can be improved, while simultaneously decreasing system costand complexity, by using lightweight structural materials with a high ratio of elastic modulus to mass density, or specific stiffness. However, materials presently suitable for fabrication of prototypes all exhibit unremarkable specific stiffness. Reinforcing a ductile metal with ceramic particles results in a composite material, commonly called a metal matrix composite MMC, that super imposes the toughness of the metal with the stiffness and thermal stability of the ceramic. Although improvements in specific stiffness of over 100 percent are possible, MMCs are almost never used in prototypes because they require long lead times and cannot be shaped into complex geometries with existing methods. This document describes progress toward developing aluminum matrix composites that can be processed with selective laser melting SLM, a 3D printing method that uses a high intensity laser to consolidate thin layers of metal powder. Feedstock powders are being developed specifically for the SLM process, and laser consolidation is being conducted with a custom built SLM testbed that allows process parameters to be broadly tuned to prevent defects and produce optimal microstructures.
- Manufacturing and Industrial Engineering and Control of Production Systems
- Laminates and Composite Materials