Microstructure of an Al-Mn-Be-B alloy

The aim of this work was to determine the effect of boron on the solidification and processes taking place during heat treatment of an Al-Mn-Be-based alloy. Several phases formed upon slow cooling of the investigated alloy Al89Mn2Be2B7: BeB12, AlBeB, T-Al15Mn3Be2, Al6Mn and aluminium solid solution (Alss). An icosahedral quasicrystalline phase (IQC) was formed during rapid solidification by melt spinning; partly dissolving Be and B, while the remaining Be and B precipitated as a ternary compound AlBeB. The primary IQC persisted within the microstructure up to 400 °C, whilst at temperatures above 450 °C the initial microstructure started to transform quickly into AlBeB, Al6Mn and Alss, which appeared to be the stable phases below the alloy's solidus temperature. The hardness remained almost unchanged up to 400 °C, whilst at temperatures above 450 °C it dropped abruptly.