Application of cast Al–Si alloys in internal combustion engine components

Abstract

Excellent thermal conductivity and lower density make Al-Si alloys a suitable alternative for cast iron in the fabrication of engine components. The increase in the maximum operation temperature and pressure of engines necessitates improving the thermomechanical fatigue performance of Al-Si alloys. This paper has two major parts focussing on the use of Al-Si based alloys in cylinder heads and engine blocks. In the first part, the structural stress-strain and material property requirements of cylinder heads are discussed. In addition, the physical and mechanical properties of different competing materials used in the manufacture of engine components are reviewed. The physical metallurgy, solidification sequence and thermal conductivity of Al-Si based alloys are reviewed. Also discussed is the effect of microstructural features on thermomechanical fatigue lifetime. This part also includes an overview of the strengthening mechanisms of cast Al-Si alloys, by dispersed phases and heat treatment. Demands to improve fuel economy and reduce emissions necessitate modifications in the materials and design of engine blocks. Wear resistance and low friction coefficient are the major characteristics required for engine block materials. In the second part, the most promising alternative approaches to manufacturing liner-less Al-Si alloy cylinder blocks are elaborated.

Interaction between molybdenum and manganese to form effective dispersoids in an Al–Si–Cu–Mg alloy and their influence on creep resistance

“…Over the past decade Al cast alloys possessing high strength-toweight ratio have been used for powertrain applications [1][2][3][4]. Modern lightweight engine blocks and cylinder heads are made of aluminum alloys of different compositions [3][4][5].…”

Effects of Cu content and Cu/Mg ratio on the microstructure and mechanical properties of Al–Si–Cu–Mg alloys

“…AleSi foundry alloys are widely used in the automotive industry due to their low density, good corrosion resistance and excellent castability [1]. In order to achieve high strength and good ductility, the commercial AleSi alloys are normally alloyed with Mg and/or Cu elements, such as A356 and A319, etc.…”

Silicon particle pinhole defects in aluminium–silicon alloys

“…The most common and important known Fe-intermetallic is the b-Al 5 FeSi phase. This normally forms large and elongated platelets [21], which are at times connected, at times not, to silicon particles [22] and are known to severely reduce the alloy ductility [23]. Another common Fe-containing phase is the a-Al 8 Fe 2 Si intermetallic, which has a Chinese-script morphology [19].…”