Effect of Excess Silicon on the Formation of Ti3SiC2 Using Free Ti/Si/C Powders Synthesized via Arc Melting

Abstract

The aim of this study is to investigate the effect of excess silicon on the formation of Ti3SiC2 from free Ti/Si/C powders synthesized via arc melting. The reactant mixture was prepared according to the off-stoichiometric ratio of 3Ti : (x+1)Si : 2C, where x (excess Si) varied from 0 to 0.5. Samples were analyzed using X-ray diffractometry (XRD), field-emission scanning electron microscopy (FESEM), and energy-dispersive spectroscopy (EDS). The relative density and porosity of products were calculated using the Archimedes method. Through optimization of the arcing schedules (time) and excess Si amounts, 86.9 wt% of Ti3SiC2 with a relative density of 86% was obtained. For all products, Ti3SiC2 was identified as the main phase, while TiC, TiSi2, and Ti5Si3 were identified as secondary phases. Ti3SiC2 grains were in the form of elongated platelets; they were nucleated and grew on the surface of equiaxed TiC grains. The microporosity present in the TiC-equiaxed grains affected the density and porosity of the products.