ADDITIVE MANUFACTURING OF COMPLEX-SHAPE GRADED TiC-STEEL COMPOSITES

Asaf Levy ¹ Aslan Miriyev ² Amy Elliott ³ Sudarsanam Suresh Babu ⁴ Nachum Frage ¹

¹Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel
²Department of Mechanical Engineering, Columbia University, New York, New York, USA
³Oak Ridge National Laboratory, Manufacturing Demonstration Facility, Knoxville, TN, USA
⁴Department of Mechanical, Aerospace and Biomedical Engineering, University of Tennessee, Knoxville, TN, USA

Functionally graded ceramic-metal composites (cermets) exhibit wide range of properties, controllably altered throughout a single material piece. One of the long standing challenges has been the inablility to fabricate cermet parts with complex geometries. The present work demonstrates a novel integrated approach for fabrication of fully dense complex-shape graded TiC/steel composites by 3D-printing of TiC preforms and subsequent free infiltration with molten carbon steel. Thermodynamic analysis allowed to predict the final composition of the phases and design composites with tailored properties. Gradient in hardness of the composites was achieved by using titanium carbide with different stoichiometries (TiC_x) which provides different carbon contents in the steel across the printed part during an infiltration, and hence- different properties of the steel after solidification and heat treatments. The microstructural characteristics of the graded cermets and the effect of the composition on hardness gradient after the heat treatment are discussed in details. The suggested approach opens the door for a wide range of advanced cermet applications in tooling, wear, aerospace and ballistic fields.