Response Surface Methodology-Based Optimization of AZ91 Composites Reinforced with Short Carbon Fibers for Enhanced Mechanical and Wear Properties

This study aims to enhance the mechanical and wear properties of AZ91 magnesium alloy by reinforcing it with 23 vol.% short carbon fibers (SCFs) aligned in normal (AZ91C-N) and parallel (AZ91C-P) orientations via squeeze-casting. The microstructure and elemental distribution maps were analyzed using an advanced SEM-EDS system. A response surface methodology (RSM) based on a Face-Centered Composite Design (FCCD) was employed to optimize the properties under varying temperature (20–300 °C) and wear load (1–5 N) conditions. The ultimate compressive strength (UCS), yield strength (YS), reduction in height at fracture (Fr), reduction in height at maximum stress (Sr), volume loss, and wear rate were analyzed and optimized. ANOVA confirmed the significant influence of the experimental parameters. A statistical model was developed, with validation showing deviations less than 0.05. The optimized conditions resulted in a UCS of 253 MPa, a YS of 193 MPa, an Fr of 26.1%, an Sr of 21.7%, a volume loss of 0.066 cm3, and a wear rate of 840 cm3/m. The worn surface and surface roughness were also investigated and discussed. The orientation of SCFs significantly influenced wear resistance and surface roughness. This study demonstrates the effectiveness of RSM in optimizing AZ91-SCF composites for high-performance applications.