Influence of Mg on reaction and properties of Al–Si/TiC nanocomposites

Titanium carbide (TiC) is used in aluminum (Al)-based nanocomposites for its simple synthesis, good wettability, and advantageous strengthening effects. However, the silicon (Si)–TiC reaction greatly hinders its widespread applications in Al–Si based nanocomposites (e.g., AlSi10Mg system). In this study, we systematically analyzed the reaction mechanism between Si and TiC in AlSi10Mg alloy and demonstrated an accelerated reaction with Mg addition. Together with the phase diagram calculation, study of microstructural evolution and mechanical property has confirmed the reaction dynamics. Even though the strength is retained in AlSi10Mg–TiC nanocomposites, the Mg-assisted chemical reaction greatly lowers the ductility to 1.39% after heat treatment. With this understanding, other elements with minimal effects on the reaction between Si and TiC, e.g., silver (Ag), have been proposed to solve this processing bottleneck. TiC only shows a moderate reaction in the AlSi10Ag alloy, which is comparable to AlSi10–TiC and helps maintain the ductility (>3%) even after the heat treatment. This study is of interest for the optimal design and performance enhancement in TiC-reinforced Al–Si nanocomposites.