Impact of beryllium additions on thermal and mechanical properties of conventionally solidified and melt-spun Al-4.5 wt.%Mn-x wt.%Be (x＝0, 1, 3, 5) alloys

摘要

The influence of beryllium (Be) addition on the quasicrystal-forming ability, thermal and mechanical properties of Al-4.5 wt.%Mn-x wt.%Be (x = 0, 1, 3, 5) alloys was investigated in this study. Quasicrystalline Al-Mn-Be alloys were synthesized by the conventionally casting and melt spinning techniques. The microstructures of the samples were characterized by scanning electron microscopy (SEM) and the phase composition was identified by X-ray diffractometry (XRD). The phase transition during the solidification process was studied by differential scanning calorimetry (DSC) and differential thermal analysis (DTA) under an Ar atmosphere. The mechanical properties of the conventionally solidified (CS) and melt-spun (MS) samples were measured by a Vickers micro-hardness indenter and tensile-strength tests. The Al-4.5 wt.%Mn alloy has a hexagonal structure and minor dendritic icosahedral quasicrystalline phase (IQC) precipitates surrounded by an α-Al matrix. Addition of Be into the Al-4.5 wt.%Mn alloy generates intermetallic Be_4AlMn and IQC phases with the extinction of the hexagonal phase, and the fraction of IQC increases continuously with the increase in Be content. A considerable improvement in microhard-ness and tensile strength values was observed due to the addition of Be in different percentages into the composition.