Studies on the influence of stirrer blade design on the microstructure and mechanical properties of a novel aluminum metal matrix composite

In the present work, the influence of stirrer blade design on the dispersion of reinforcement particles in the aluminum metal matrix was studied extensively through experiments and also simulated them using the computational fluid dynamics (CFD) method. The microstructure and mechanical properties of the produced metal matrix composites (MMCs) were studied. The analysis of the microstructure was performed using an optical microscope to visualize the reinforcement distribution and binding within the matrix. Further, field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD) were used to characterize the MMCs. The experimental density was assessed using the Archimedes method, and the theoretical density was determined using the mixture law to determine the percentage of porosity in the MMCs. Hardness, compression, and tensile testing were performed on the produced samples. A three-dimensional computational method was used to predict the flow field of aluminum melt and study the influence of the blade design on the distribution of the reinforcement. Experimental results validated the CFD recommendation on the blade design. The CFD recommendation was based on the structure, power number, and the number of blades, and accordingly, the four-blade flat stirrer (B4) design was the best. The experimental results also corroborated the CFD recommendation with the four-blade flat stirrer design achieving the highest compressive strength (642 MPa), highest hardness (45 HRB), and highest tensile strength (206 MPa) among the five different blade designs investigated.