Figure 1.

Schematic representation of the solidification-induced formation of a 2D network of percolating structures with enhanced heat-transfer properties. In the liquid state (left figure), the clusters are randomly dispersed. During phase transition (middle figure), needlelike structures develop and the clusters experience a stress field, which drives them toward the grain boundaries. The formation of a quasi-2D percolating network is complete in the solid state (right figure), which causes a large enhancement in thermal conductivity. The inset shows the expanded view of a cluster, where the backbones and dead ends consisting of individual nanoinclusions are seen. Thermal conductivity enhancement within a cluster is primarily through phonon-mediated heat transfer via the interconnected backbones, which span the entire length of a cluster.