Title: The effect of process parameters on the microstructure an‎d mechanical properties of AA6061-SiC composite produced by the extrusion method

10/15/2026 12:00:00 AM

Metal–matrix composites (MMCs) based on AA6061 reinforced with silicon carbide (SiC) particles are widely used in the aerospace an‎d automotive industries due to their favorable strength-to-weight ratio. Precise control of hot-extrusion parameters is critical for achieving a desirable microstructure an‎d optimal mechanical properties in these composites. This study presents a systematic investigation of the influence of two principal hot-extrusion parameters—extrusion ratio an‎d extrusion temperature—on the microstructure an‎d mechanical properties of AA6061–SiC composites. The objective was to identify the combination of extrusion ratio an‎d temperature that yields the best mechanical performance an‎d a favorable microstructural state. Composite billets were prepared by coating AA6061 billets with SiC powder an‎d subsequently subjected to hot extrusion. A two-factor experimental design with three levels for each factor was implemented: extrusion ratios of 6, 12 an‎d 18, an‎d extrusion temperatures of 300, 350 an‎d 400 °C. Post-extrusion characterization included optical an‎d electron microscopy for microstructural examination, energy-dispersive X-ray spectroscopy (EDS) for particle distribution an‎d elemental mapping, an‎d Brinell hardness testing to eva‎luate mechanical response. Annealing an‎d surface preparation procedures were carried out in accordance with relevant ASTM stan‎dards. The highest mean Brinell hardness (54 HB) was observed for specimens extruded at an extrusion ratio of 6 an‎d an extrusion temperature of 350 °C. Increasing the extrusion ratio to 18 an‎d the extrusion temperature to 400 °C produced a reduction in final hardness, which is attributed to the dominance of dynamic softening mechanisms such as dynamic recrystallization. EDS analysis revealed a non-uniform longitudinal distribution of SiC nanoparticles along the extrudate: silicon an‎d carbon concentrations increased from the initial region toward the mid an‎d end regions of the extruded profile. A hardness gradient was also detected along the sample length, with hardness decreasing by approximately 5.7% from the initial toward the terminal section. These results indicate that lower extrusion ratios combined with an intermediate extrusion temperature are favorable for retaining higher hardness in AA6061–SiC composites produced by hot extrusion, while higher ratios an‎d temperatures promote dynamic softening an‎d reduced hardness.

اكستروژن‌گرم , نسبت اكستروژن , دماي اكستروژن , كامپوزيتAA6061-SiC

hot extrusion , extrusion ratio , Extrusion temperature , : AA6061-SiC composite

Amirreza Hajian

Dr. Seyed Hossein Razavi Dr. Bagher Mohammad Sadeghi