Synthesis of TiC–Ti Composites via Mechanical Alloying/Spark Plasma Sintering Using Ti and C Powders

Abstract

In this study, a TiC–Ti composite has been synthesized as a novel cermet without using rare elements like W, Co, and Ni. The mechanical properties of the prepared TiC–Ti composite are improved by utilizing Ti and C powders as raw materials in the mechanical alloying process. The effects of the non-equilibrium state during mechanical alloying on the characteristics of the composite have been analyzed. The results indicate that for short milling times, the addition of 25 mol% of C results in the Ti phase size in the sintered compact typically being on the order of several tens of micrometers, and unreacted C remains in the sample. A milling time of ≥21.6 ks affords a TiC–Ti composite containing approximately 80% fine TiC phase with an average size of 1–2 µm. As the milling progresses, the crystalline size of the Ti phase decreases, while the lattice strain increases. Prolonged milling improves the diffusion of C into Ti; a milling time of 36 ks at a low temperature of ∼700 K results in the formation of TiC as well as uniform diffusion of C throughout the Ti phase. Sintering the composite powder milled for 36 ks affords a Vickers hardness of approximately 700 Hv, which is similar to that of a TiC-35% Ni cermet.

Fig. 10 Schematic of the microstructure evolution during the sintering of the powders milled for (a) short time (3.6 ks) and (b) long times (21.6 and 36 ks).