“…The main drawback, in this case, is the high toxicity of the added element. Other authors [18,37] reported Ce as an effective addition improving the I-phase formation in Al-Mn alloys under different solidification conditions; nonetheless, this was more recently disputed by Coury et al [38]. The addition of Ce was found to stabilise the intermetallic phase Al 20 Mn 2 Ce with a cubic structure reported previously in similar alloys [39].…”
Al-rich 94Al-6Mn and 94Al-4Mn-2Fe alloys were suction-cast to evaluate the feasibility of obtaining bulk quasicrystal-strengthened Al-alloys at intermediate cooling rates alloyed with non-toxic, easily accessible and affordable additions. The influence of different cooling rates on the potential formation of a quasicrystalline phase was examined by means of scanning and transmission electron microscopy, X-ray diffraction and differential scanning calorimetry. Increased cooling rates in the thinnest castings entailed a change in sample phase composition. The highest cooling rates turned out to be insufficient to form an icosahedral quasicrystalline phase (I-phase) in the binary alloy. Instead, an orthorhombic approximant phase occurred (L-phase). The addition of Fe to the 94Al-6Mn binary alloy enhanced the formation of a quasicrystalline phase. At intermediate cooling rates of 10 2 -10 3 K/s, various metastable phases were formed, including decagonal and icosahedral quasicrystals and their approximants. Rods (1 mm in diameter) composed of I-phase particles embedded in Al matrix exhibited a hardness of 1.5 GPa, much higher than the 1.1 GPa of 94Al-6Mn.
“…The main drawback, in this case, is the high toxicity of the added element. Other authors [18,37] reported Ce as an effective addition improving the I-phase formation in Al-Mn alloys under different solidification conditions; nonetheless, this was more recently disputed by Coury et al [38]. The addition of Ce was found to stabilise the intermetallic phase Al 20 Mn 2 Ce with a cubic structure reported previously in similar alloys [39].…”
Al-rich 94Al-6Mn and 94Al-4Mn-2Fe alloys were suction-cast to evaluate the feasibility of obtaining bulk quasicrystal-strengthened Al-alloys at intermediate cooling rates alloyed with non-toxic, easily accessible and affordable additions. The influence of different cooling rates on the potential formation of a quasicrystalline phase was examined by means of scanning and transmission electron microscopy, X-ray diffraction and differential scanning calorimetry. Increased cooling rates in the thinnest castings entailed a change in sample phase composition. The highest cooling rates turned out to be insufficient to form an icosahedral quasicrystalline phase (I-phase) in the binary alloy. Instead, an orthorhombic approximant phase occurred (L-phase). The addition of Fe to the 94Al-6Mn binary alloy enhanced the formation of a quasicrystalline phase. At intermediate cooling rates of 10 2 -10 3 K/s, various metastable phases were formed, including decagonal and icosahedral quasicrystals and their approximants. Rods (1 mm in diameter) composed of I-phase particles embedded in Al matrix exhibited a hardness of 1.5 GPa, much higher than the 1.1 GPa of 94Al-6Mn.
“…Be addition is also known for being carcinogenic and causing other serious diseases, such as berylliosis [21], thus, other elements that could enhance the I-phase formation during conventional casting processes are desirable. Additionally, cerium-previously reported as promoting I-phase formation under different solidification conditions [22,23]-was recently disputed by Coury et al [24]. Some other works show that in aluminum alloys alloyed with Mn, Cu, Mg, and Si, primary I-phase particles with petal morphology can be formed at low cooling rates [25].…”
Abstract:The aim of the presented research was to study the influence of Cr, Co, Ni, and Cu additions on the formation of quasicrystalline particles in the 94Al-6Mn base alloy during casting at intermediate cooling rates. Based on the obtained results, Cu and Ni enhance quasicrystalline phase nucleation compared to the unmodified binary composition. In the case of Cu addition, formation of a quasicrystalline phase takes place along whole thickness of the prepared casting, but its fraction and morphology depends on the cooling rates present in different parts of the sample. Based on the previous works on the beneficial effect of Fe addition, a quaternary alloy containing both Fe and Cu was prepared to evaluate the effect of the simultaneous presence of these elements on the microstructure of the obtained castings.
“…Most quasicrystals, however, can only be fabricated by rapid solidification of metallic melts. These "metastable" quasicrystals are found in several Al-based systems, such as Al-Mn [34], Al-Cr [6], Al-V [6], Al-Fe-Cr [7], and in their chemical modifications [13,35,36,37]. Electron diffraction patterns of a natural decagonal quasicrystal, using (a) selected area and (b) convergent beam electron diffraction pattern.…”
Section: General Aspects Of Quasicrystals and The Motivation For Usinmentioning
confidence: 99%
“…Adding rare-earth elements, such as Ce, was one of the first attempts to increase stability of the quasicrystalline phase [78]. However, a recent study by Coury et al [34] showed, using electron microscopy, that Ce is virtually absent within the Al-Mn quasicrystalline structure and its presence leads to the formation of a crystalline Al-Mn-Ce-based intermetallic. Stan-Głowińska et al assessed the influence of Fe addition to the Al-Mn quasicrystal [36,86,87].…”
Section: Al-matrix Mmcs Reinforced With Nano-sized Quasicrystalsmentioning
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