Remelting of In Situ Fe‐xTiC Metal Matrix Composites by the Sessile Drop Method: Characteristic Temperatures and Microstructural Analysis

Abstract

The remelting of Fe‐xTiC metal matrix composites (MMCs) is studied using the sessile drop method. This is to determine the conditions needed for the complete dissolution of TiC precipitates in the Fe‐based melt. Samples with different amounts of TiC (2, 3.5, and 5 wt%) are analyzed in a hot‐stage microscope (HSM), capturing the softening and melting temperatures. A Cr‐alloyed steel is selected as a matrix. Consequently, the presence of TiC elevates the melting initiation temperature above the melting point of pure iron (e.g., 1659 ± 10 °C for Fe‐5TiC). Furthermore, samples with higher TiC amounts exhibit higher melting initiation temperatures. This trend is confirmed by differential scanning calorimetry measurements, conducted on the representative Fe‐xTiC samples. Microstructural examinations of the solidified (HSM) samples identify two distinct TiC precipitate morphologies: primary blocky/cubic and secondary eutectic plate like. For instance, the Fe‐5TiC sample contains numerous blocky/cubic precipitates (7.5 ± 3.1 μm) clustered at the upper cross‐ section, while secondary plate‐like precipitates (20.4 ± 11.8 μm) are uniformly distributed in eutectic assemblies with the matrix. This study provides meaningful insights for optimizing the production of as‐cast and as‐atomized Fe‐TiC MMCs, particularly in selecting reinforcement levels and homogenization temperatures for complete TiC dissolution.