Role of Fe substitution and quenching rate on the formation of various quasicrystalline and related phases

Bulletin of materials science

R S Tiwari¹  O N Srivastava¹  Varsha Khare¹ 

[1] Department of Physics, Banaras Hindu University, Varanasi 221 005, India$$Department of Physics, Banaras Hindu University, Varanasi 221 005, IndiaDepartment of Physics, Banaras Hindu University, Varanasi 221 005, India$$

关键词: Quasicrystals;    icosahedral and decagonal phases;    quenching rate.;   

DOI  :  

学科分类：材料工程

来源: Indian Academy of Sciences

【 摘 要 】

We have investigated Fe substituted versions of the quasicrystalline (qc) alloy corresponding to Al₆₅Cu₂₀(Cr, Fe)₁₅ with special reference to the possible occurrence of various quasicrystalline and related phases. Based on the explorations of various compositions it has been found that alloy compositions Al₆₅Cu₂₀Cr₁₂Fe₃ and Al₆₅Cu₂₀Cr₉Fe₆ exhibit interesting structural phases and features at different quenching rates. At higher quenching rates (wheel speed ∼ 25 m/sec) all the alloys exhibit icosahedral phase. For Al₆₅Cu₂₀Cr₁₂Fe₃ alloy, however, both the icosahedral and even the decagonal phases get formed at higher quenching rates. At higher quenching rate, alloy having Fe 3 at% exhibits two bcc phases, bccI (ð‘�? = 8.9 Ã�?) and bccII (ð‘�? = 15.45 Ã�?). The orientation relationships between icosahedral and crystalline phases are: Mirror plane ∥[001]_{bcc I} and [351]_{bcc II}, 5-fold ∥ [113]_{bcc II} and 3-fold ∥ [110]_{bcc II}. At lower quenching rate, the alloy having Fe 6 at% exhibits orthorhombic phase (ð‘�? = 23.6 Ã�?, ð‘�? = 12.4 Ã�?, ð‘�? = 20.1 Ã�?). Some prominent orientation relationships of the orthorhombic phase with decagonal phase have also been reported. At lower quenching rate (∼ 10 m/sec), the alloy (Al₆₅Cu₂₂Cr₉Fe₆) shows the presence of diffuse scattering of intensities along quasiperiodic direction of the decagonal phase. For making the occurrence of the sheets of intensities intelligible, a model based on the rotation and shift of icosahedra has been put forward.

【 授权许可】

Unknown