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New three-dimensional printing technology (3DP) developed at MIT was tried as a manufacturing method to fabricate ceramic preforms for a discontinuously reinforced metal matrix composites. Minor modifications to the “legacy” 3DP technology allowed to produce such preforms successfully. Preforms were then infiltrated with liquid aluminum resulting in composite materials as strong as produced via conventional methods. Net shape connecting rod preforms were 3D-printed and used to produce composite connecting rods without building any molds or tooling using novel Tool-less Mold™ technology.

Net-shape aluminum matrix composite components and test specimens were produced through an advanced pressure infiltration process where molten alloys are infiltrated into ceramic preforms. Test specimens were cast with 4 aluminum alloys with alumina and SiC reinforcements. Specimens were heat treated to T6 and T7 conditions and to a special condition wherein intermetallic particles are precipitated at internal interfaces. Alumina reinforced materials were generally stronger and tougher than silicon carbide reinforced materials. Maximum flexure strengths of 653 and 683 MPa were achieved through alumina reinforced 520 and 295 alloys, respectively. Fracture toughness and Charpy impact values were also determined.