3D Architecture and Load Partition in Eutectic Al‐Si Alloys

Abstract

The changes of the three dimensional architecture of a eutectic AlSi12 alloy during heat treatment are revealed by means of synchrotron holotomography. The non‐destructive nature of the holotomography technique allows to analyze the same volumes in different thermal conditions. The results show a disintegration of the interconnected eutectic Si‐lamellae into isolated elongated particles. The load carrying capacity of both types of Si morphologies is studied by in situ neutron diffraction during compression tests. The experimental results are compared to those obtained using a micromechanical model developed for metal matrix composites based on a homogenization approach. The correlation between experiments and calculations shows that the interconnectivity of Si must be considered to account for the strength exhibited by the eutectic alloy. The present study bridges the gap between the already available two‐dimensional studies of architecture and properties of the binary AlSi12 alloy and new three‐dimensional studies of more complex systems based on this alloy.

Sub-micrometre holotomographic characterisation of the effects of solution heat treatment on an AlMg7.3Si3.5 alloy

“…The elevated temperature strength and the hardness of the material decrease after the solution heat treatment in a similar way as reported for eutectic Al–Si alloys [13]. The alloy in as-cast condition as well as after solution treatment was tested in an overaged condition (2 h/300 °C), to minimise precipitation strengthening.…”

“…The mechanical properties of multiphase materials are strongly dependent on the internal architecture of the constituent phases [13]. Thus, the determination of morphological parameters, like size, shape and interconnectivity of the phases or contiguity between them [14] are important to understand their macroscopic behaviour.…”

Effect of solution heat treatment on the internal architecture and compressive strength of an AlMg4.7Si8 alloy

“…[12]) can be observed in the micrographs shown in Figs. 1 and 2 parallel to the morphological changes occurring in the Mg 2 Si phase.…”

“…The internal architecture of multiphase alloys, i.e. the volume fraction and spatial arrangement of the microstructural phases, plays a vital role in determining their strength [12]. Therefore, the quantification of morphological parameters such as interconnectivity of phases or contiguity between them [13] is essential to understand the macroscopic behaviour of these alloys [14].…”

The effect of spheroidisation heat treatment on the creep resistance of a cast AlSi12CuMgNi piston alloy

“…Particularly, rigid phases such as eutectic Si and intermetallic compounds can carry part of the load transferred from the matrix if they are present in sufficiently large volume fractions (e.g. [2][3][4][5][6][7]). …”