The Influence of Alloying Elements on the Microstructure and Properties of Al-Si-Based Casting Alloys: A Review

Abstract

The excellent casting behavior and mechanical and corrosion properties of aluminum-silicon (Al-Si)-based alloys make them ideal for the manufacture of lightweight components with complex geometries. However, these properties depend directly on their microstructure, which, in its turn, is strongly affected by the composition of the alloy, among other factors. Several elements can be added to the material aiming to promote microstructural changes, e.g., grain refinement, optimization of phase morphology and distribution, and precipitation strengthening. Efforts are continuously put into such enhancements of cast Al alloys since they lead to quality improvements that allow for weight reduction and safety increase. Considering the technological relevance of the subject, this paper provides an overview of the research focused on the addition of alloying elements to these alloys, with a greater focus on Al-Si-based systems and the comprehension of the effects of these additions on their microstructure and properties.

Additive Manufacturing for Rapid Sand Casting: Mechanical and Microstructural Investigation of Aluminum Alloy Automotive Prototypes

“…From the highest magnifications of Figure 7, only a slight qualitative difference can be observed Figure 8 reports a comparison of SEM micrographs conducted on the same EN AC 42100-T6 SC and RSC specimens analyzed in Figure 7 optical microstructures. SEM investigations and EDS analysis confirmed the previously described microstructure, identifying the intermetallics, coherently with the literature [29,30], as β-Al5FeSi phase (red arrow) and π-AlFeMgSi Chinese script (yellow arrow). Please note that even if π-AlFeMgSi is a Fe-rich intermetallic that may cause the embrittlement of the alloy, the conversion of the needle-like β-AlFeSi phase into the Chinese script π-AlFeMgSi reduces the deleterious effects of the former on mechanical properties [30].…”

“…SEM investigations and EDS analysis confirmed the previously described microstructure, identifying the intermetallics, coherently with the literature [29,30], as β-Al5FeSi phase (red arrow) and π-AlFeMgSi Chinese script (yellow arrow). Please note that even if π-AlFeMgSi is a Fe-rich intermetallic that may cause the embrittlement of the alloy, the conversion of the needle-like β-AlFeSi phase into the Chinese script π-AlFeMgSi reduces the deleterious effects of the former on mechanical properties [30]. This mechanism is known to occur with the increase in Mg content in the presence of Fe [31].…”

Fabrication and characterization of ADC-12 hybrid composites utilizing lemon grass ash and boron nitride through stir-squeeze casting method

“…However, being exorbitant and inadequate supply of traditional reinforcing materials, particularly in transitionally industrialized nations, poses severe challenges to manufacturing ADC 12 with discontinuously reinforced elements. Although ADC 12 has been found to have low fracture toughness, weak ductility, and unpredictable corrosion behaviour, it has nonetheless piqued the curiosity of researchers [3].…”

Deciphering Microstructures and Phases of Gas-Atomised Novel Al-Fe-Si-Cr-Ni Alloys

“…The presence of iron in Al-Si alloys increases properties at high temperatures and hardness but decreases corrosion resistance, fluidity, and plastic properties [4]. As previously reported, iron content exceeding 0.5% results in the formation of brittle intermetallic phases such as the Al 5 FeSi (β) phase, which has an adverse impact on the mechanical properties of the alloy due to its needle-like morphology [5].…”