October_AMP_Digital

A D V A N C E D M A T E R I A L S & P R O C E S S E S | O C T O B E R 2 0 1 7 1 9 Fig. 5 — Cross-section micrograph of a functionally graded AMIPC in which the 316L volume fraction decreases from le to right. The reason for this microcracking be- havior is shown in the inset, which re- veals that the cracks in the A356 are bridged by the more ductile phase—the 316L reinforcement. Without the con- tinuous 316L structure throughout the specimen, the composite would have failed due to cracks propagating unin- terrupted in the A356 material. To demonstrate the capability of this technique to lend further cus- tomization to the design of features within parts, the ORNL/Rice team has produced a functionally graded AMIPC, shown in Fig. 5, whose lattice structure, and thus local properties, were varied across the part by changing the volume fraction of 316L from 20% to 70%. Beyond exploiting AMIPCs to de- liver specific material properties, AMIPCs can also expand to other ma- terials systems, such as metal-ceram- ic or metal-glass systems, that can yield properties unattainable through combinations of metallic alloys. The black region in Fig. 6 illustrates the hybrid properties of AMIPCs that can be achieved by choosing different Fig. 6 — Ashby map showing specific yield strength and thermal conductivity for AMIPCs tested in this work. constituent materials with a mix of var- ious properties. Select materials could be used for lightweight high-strength heat transfer applications, such as heat exchangers, storage heaters, and thermal buffers. The initial results demonstrated during testing of AMIPCs illustrate how new opportunities may arise through the optimization of weight, thermal con- ductivity, and strength that can be achieved with conventional low-cost materials. SUMMARY The ORNL/Rice team proof of concept work has demonstrated how AMIPCs can enable new opportunities in the world of industrial design and materials selection by combining AM with casting technology. In particular, this processing strategy can be used to pattern the components at the sub-mil- limeter scale, providing exceptional control over microstructure and signifi- cant advantages over conventional pro- cessing technologies for manufacturing