Influence of boron on the creep behavior and the microstructure of particle reinforced aluminum matrix composites

Abstract

The reinforcement of aluminum alloys with particles leads to the enhancement of their mechanical properties at room temperature. However, the creep behavior at elevated temperatures is often negatively influenced. This raises the question of how it is possible to influence the creep behavior of this type of material. Within this paper, selected creep and tensile tests demonstrate the beneficial effects of boron on the properties of precipitation-hardenable aluminum matrix composites (AMCs). The focus is on the underlying microstructure behind this effect. For this purpose, boron was added to AMCs by means of mechanical alloying. Comparatively higher boron contents than in steel are investigated in order to be able to record their influence on the microstructure including the formation of potential new phases as well as possible. While the newly formed phase Al3 BC can be reliably detected by X-ray diffraction (XRD), it is difficult to obtain information about the phase distribution by means of scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM) investigations. An important contribution to this is finally provided by the investigation using Raman microscopy. Thus, the homogeneous distribution of finely scaled Al3 BC particles is detectable, which allows conclusions about the microstructure/property relationship.