GOALI: Shrinkage Porosity and Optimization of Metal-Matrix Composite Processing

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This research project involves experimental, theoretical and process optimization for the metal-matrix composites (MMCS). The experimental program involves solidifying pre-infiltrated samples of the composite and characterizing the product under a range of ambient pressure and cooling rates. This experiment will provide information on the critical pressure required for defect formation as a function of the cooling rate. A parallel theoretical program will be undertaken to numerically predict solidification pattern and porosity distribution under these process conditions. The experimental data will be used to validate the theoretical model. Finally, these findings will be utilized in a computational framework to optimize the casting operation for minimal shrinkage porosity. It is anticipated that this award will provide leveraging to obtain additional funds to study continuous-fiber-reinforced composites, the influence of reinforcement/matrix interfacial characteristics, preform temperature, matrix superheat and hydrogen content on porosity formation, and extension of experimental technique to the fabrication of large castings from pre-infiltrated small components.