Microstructural Investigation and Mechanical Performance of Al–Si Casting Alloys Modified with Titanium

One of the most common ways to improve the properties of aluminum casting alloys is through their modification. This study investigates the influence of titanium modification on the mechanical properties of Al-Si casting alloys. In this research, the Al-Si alloy which is widely used in the foundry industry, was selected as an object. The samples were liquefied in an induction furnace, and the liquid alloy was poured into sand-clay molds. The casting temperature was 750 °C. The titanium element was added to the liquid Al-Si foundry alloy in special packaging in the form of a powder from 0.1% to 0.3% of the charge and in the form of Al-10Ti master alloy from 0.1% to 0.2%. Then, samples were machined to prepare further investigations. During the research, mechanical properties including hardness and wear resistance analysis were conducted. Moreover, X-ray diffraction and microstructural analysis of the Ti modified Al-Si samples were carried out. Experimental results showed that the addition of titanium improved the mechanical properties of the samples. That is, the highest hardness was obtained at 0.1 wt.% Ti modified Al–10Ti master alloy, while titanium powder resulted in a more gradual increase in hardness. According to the wear resistance evaluations, addition of titanium within the range of 0.1–0.2 wt.% content was performed an optimal result. After, microstructural analysis, it is found that titanium promoted grain refinement and improved structural homogeneity, especially it is added in the form of Al-10Ti master alloy. The introduction of titanium into the aluminum alloy led to the formation of the Al₃Ti intermetallic compound, which contributed to the improvement of mechanical properties. These results demonstrate that the modification of Al–Si alloys with titanium can be reliably used to predict and improve mechanical properties based on comprehensive experimental analysis.