Microstructure and mechanical properties of Al/TiC and Al/(Ti,W)C nanocomposites fabricated via in situ casting method

Abstract

A modified self-propagating high-temperature synthesis in bath (SHSB) via cast was successfully used to produce the aluminium-based composites reinforced by TiC and (Ti,W)C nanoparticles. The process was managed by the addition of a moderator affecting supercooling, which consequently influences the nucleation and growth of TiC crystals. Thus, by choosing the suitable amount of moderator, not only the size and amount but also the distribution of the strengthening particles can be controlled. In this work, the research was performed in a twin-track approach: fabrication of good quality TiC particles with a homogenous distribution inside of the aluminium matrix (1), and modification of TiC particles by the addition of W in order to improve the coherency degree between both particles and the matrix and ensure more uniform distribution of the reinforcement (2). Moreover, the homogenous microstructure of Al/TiC composites was obtained. TiC particles were uniformly distributed, and no cluster in the matrix in composite up to the highest moderator content (80 wt%) was found. The compressive strength and hardness of composites reinforced with TiC particles have been significantly improved (over 100 %) compared to the base alloy while the highest values were achieved for the composite containing 80 wt% of the moderator. Moreover, the addition of W causes a significant change in the lattice parameters of TiC at the interface without changing its face-centered cubic structure (fcc). This in turn leads to improved coherence at the particle/matrix interface.