Nanocrystalline TiC-reinforced H13 steel matrix nanocomposites fabricated by selective laser melting

Additive manufacturing (AM) has a strong potential for the formation of a new class of multifunctional nanocomposites. In this study, nanocomposite feedstock powders were prepared by a mechanical alloying method based on high-energy ball milling. The evolution of constitutional phases and microstructural features of the milled powders was investigated as a function of milling time. The results showed that the milled powder particles experienced significant cold-welding during the entire milling time, with a wide size distribution. Selective laser melting (SLM), a promising AM fabrication technique, was applied to produce nanoscale 15% (by volume) TiC-reinforced H13 steel matrix nanocomposites. After SLM, uniformly dispersed nanoscale TiC particles with a mean particle size of 50 nm were obtained and a fine heterogeneous structure was observed. Relative to the unreinforced H13 steel part, the TiC/H13 steel nanocomposite parts exhibited higher hardness and elastic modulus, along with lower friction and a lower wear rate; these improvements are attributed to the combined effects of grain refinement and grain boundary strengthening. (C) 2016 Elsevier Ltd. All rights reserved.