Silicon infiltrated silicon carbide (SiSiC) is one of the most promising and economical non-oxide ceramic matrix composites for high-temperature structural applications. In recent years infiltration by Si-alloys instead of pure Si has become popular to avoid the presence of residual pure Si by replacing it with higher melting silicides. Apart from this beneficial aspect of using Si-alloys, the downsides and limitations have not received much attention and are hence not well understood. The thesis aims at developing a fundamental understanding of the reactive infiltration of carbonaceous preforms by molten Si-X alloys in general. This is achieved by developing analytical models and designing experiments to individually study various factors like wettability, porosity and pore size distribution, alloy composition, and the preform composition. The near eutectic binary Si-Zr system is used to perform experiments to observe the conjectured phenomena.