Effect of particle additions on microstructure evolution of aluminium matrix composite

The study investigates the influence of different fractions of particles (1, 2.5, 5, 8 and 10 vol.%) on microstructure of the as-extruded Al–Al4C3 composite as well as on the microstructure evolution at elevated temperatures and after cooling to room temperature. The results indicate that all the materials exhibit a stable microstructure up to 500 °C. The excellent thermal stability is secured by the dispersed nano-particles that strengthen crystallite/grain boundaries by direct interaction of the particles with moving dislocations. In addition, the higher particle contents (8 and 10 vol.%) help to suppress the deformation texture of the hot extruded solids and refine the matrix microstructure to a nanometric scale resulting in a marked enhancing of dislocation density and consequently hardness.

► Effect of different fractions of particles on microstructure of aluminium alloy.
► Dispersed nano-particles strengthen grain boundaries at elevated temperatures.
► Particle additions provide thermal stability of matrix up to 500 °C.
► Higher particle contents refine the microstructure and suppress the texture.