The Effect of the Connectivity of Rigid Phases on Strength of AlSi Alloys

Abstract

The load carrying capacity of the eutectic Si in AlSi alloys depends on its volume fraction, distribution, morphology and connectivity, namely its internal architecture. This can be modified by heat treatment at temperatures close to the eutectic point causing the spheroidisation and loss of connectivity of the eutectic Si. This decreases the load carrying capacity of the eutectic Si and, consequently, the room and high temperature strength of AlSi alloys is reduced. The presence of other phases such as ceramic short fibres and aluminides in AlSi alloys can result in the formation of hybrid three‐dimensional structures that strongly delay and/or suppress the morphological changes and the loss of connectivity of the eutectic Si. As a result, the thermo‐mechanical behaviour of these heterogeneous lightweight materials is improved and stable. These effects have been explored in the last years by the authors and the main results are compiled and presented in the present work with special emphasis in the relationship between the architecture and the strength of different AlSi‐based materials.

Effect of Cr content and heat-treatment on the high temperature strength of eutectic Al–Si alloys

“…The eutectic Al-Si based casting alloys are widely used in automotive applications (E.g., piston production) due to their good castability, high strength, light weight, good wear resistance and low thermal expansion [1][2][3][4] . However, it is well-known that the pistons are working under very extreme and complicated environment, and the materials used for pistons should be able to withstand the temperatures from 350 to 400 o C, Therefore, the superb high temperature (HT) strength of such alloys is the important design criteria [5,6] .…”

Revealing the Effect of Local Connectivity of Rigid Phases during Deformation at High Temperature of Cast AlSi12Cu4Ni(2,3)Mg Alloys

“…The strength of cast Al-Si piston alloys is given by the strength of the age-hardenable α-Al matrix and the load carrying capability of interconnected 3D hybrid networks formed by Si and various intermetallic phases [1,2,3,4,5]. The alloying elements Cu and Mg play a decisive role on precipitation strengthening of the matrix, while, together with Ni, they define the interconnectivity of the 3D networks [6,7,8,9].…”

Silicon particle pinhole defects in aluminium–silicon alloys

“…Silicon particles play a key role in the solidification, microstructural development and fracture processes of Al-Si-based alloys [1][2][3][4][5][6][7][8][9]. When these alloys are mechanically strained, it is typically observed that silicon particles within the a-aluminium matrix start fracturing gradually, essentially as soon as the alloy starts to deform plastically.…”