Enhancing the wearing resistance of TC17 alloy by nano/micro-TiC ceramic through directed energy deposition

Micro-TiC (m-TiC), nano-TiC (n-TiC), and nano/micro-TiC (n/m-TiC) ceramic particles reinforced TC17 composites were prepared using directed energy deposition (DED) technology. The microstructure, microhardness and wear properties of the composites were systematically studied. Under the same conditions, m-TiC partially melted, while n-TiC fully melted. The varying degrees of melting resulted in differences in both the level of grain refinement and the in-situ TiCX morphologies. The average grain sizes of the TC17 alloy, m-TiC/TC17, n-TiC/TC17, and n/m-TiC/TC17 composites are 76.96 μm, 39.43 μm, 20.76 μm, and 21.32 μm, respectively. The n-TiC demonstrated a superior grain refinement effect compared to m-TiC. The m-TiC/TC17 composite precipitated diverse small primary and eutectic TiCX. The n-TiC/TC17 and n/m-TiC/TC17 composites were mainly composed of primary dendritic and rod-like TiCX, with no eutectic phases observed. The n/m-TiC/TC17 composite showed the highest hardness (~ 579.417 HV0.2) and best wear resistance (0.0592mg/m), with a 44.4% hardness increase and a 51.4% wear rate decrease compared to TC17 alloy. In contrast, m-TiC/TC17 and n-TiC/TC17 composites showed hardness increases of 4.55% and 35.99%, and wear rate reductions of 18.7% and 43%, respectively.