Al-TiB2 micro/nanocomposites: Particle capture investigations, strengthening mechanisms and mathematical modelling of mechanical properties

The interactions between suspended ceramic particles in composite slurry and advancing solidification front take place during liquid state processing of particle reinforced metal matrix composites. The introduced solidification models in this research propose the possibility of nanoparticle engulfment by solidification front during gravity casting of molten composite. Results indicate that the strengthening mechanisms are considerably affected by the degree of particle engulfment and the quality of particle distribution in solid matrix. Microstructural studies show that nanoparticles are either engulfed inside metal grains or pushed by solidification front into the aluminum-silicon interface. The comparison of mechanical properties with the changes of secondary dendrite arm spacing proposes the dominance of Orowan strengthening mechanism in the samples reinforced by 0.5 vol% nanoparticles. The highest tensile properties are achieved in the composites reinforced by 1.5 vol% TiB2 nanoparticles. Experimental results of mechanical tests are constructed to create a multi-input and multi-output model by using a Neural Networks-Levenberg Marquardt Algorithm (NN-LMA). It is reported that the NN- LMA model is highly accurate (the margin of error is less than 5%) to predict the mechanical properties of Al-TiB2 composites.