Microstructural Evolution, Mechanical Strengthening, and Tribological Performance of Titanium-Modified Hypereutectic Al–23Si Alloys

Hypereutectic Al–23Si alloys possess good mechanical properties, but large primary silicon particles may restrict their strength and flexibility. The present work aims to investigate the influence of adding Ti with different weight percentages (0.0, 0.2, 0.4, 0.6 and 0.8 wt.%) on the structural, microstructural and mechanical properties of cast Al–23Si alloys. The tests considered were Vickers hardness, tensile, compression, field-emission scanning electron microscopy (FESEM–EDS) and Fourier-transform infrared spectroscopy (FTIR). In the example data set, the average size of the crystallites increases from 38.05 nm to 47.67 nm, and the apparent microstrain and estimated dislocation density decrease. FTIR analysis shows possible vibrational bands for surface oxides and the simulated microstructural observations suggest that the initial silicon particles are reduced in size from about 43 to 24 µm at 0.6 wt.% Ti. The example mechanical results indicate that the best hardness (140.40 HV), ultimate tensile strength (211 MPa), yield strength (151 MPa), Young’s modulus (87.8 GPa) and elongation (1.62%) are attained with ATS3 (0.6 wt.% Ti), which are better than the unmodified alloy by 28.3%, 33.5%, 34.8%, 6.4%, and 35.0%, respectively.