Submit Manuscript | http://medcraveonline.com Introduction The development of materials has provided researchers with more powerful instruments, methods and building blocks to create outstanding materials technology and devices. 1 The discovery of new materials have provided scientists, maybe for the frst time, with the possibility of exploring, modifying and constructing an artifcial world as complex as nature from a fundamental level. The intermetallic materials, having very high specifc strength but poor ductility, require special processing techniques to develop appropriate microstructure for adequate ductility or toughness for successful use in structural applications. 2 Non–equilibrium processing of materials is often advantageous due to the possibility of producing metastable microstructure with improved properties. 3–5 Among the no equilibrium techniques developed during the past few decades to synthesize novel materials include rapid solidifcation from the liquid state, mechanical alloying/ milling, plasma processing, vapour deposition, ion or electron or neutron irradiation. 6,7 As an important and emerging class of no equilibrium materials, such as quasicrystalline alloys have drawn wide attention in the recent years. 8–10 Quasicrystalline materials are of interest because of their fundamentally new microstructure and phase dependent novel properties not manifested by identical materials with coarse microstructure. 11 Improvement in terms of mechanical properties includes both increase in strength as well as ductility and fracture toughness due to a periodic structures. Aside from the peculiar structures, quasicrystals also exhibit much unexpected properties such as high hardness, low surface energy, high oxidation resistance, and low thermal conductivity, which make them attractive for technological applications. 12,13 These materials can also be used as dispersions, coatings, functional devices, consolidated materials, etc. Rapid solidifcation of liquid metals and alloys can lead to refnement of grain size, formation of new metastable quasicrystalline phases by suppression of equilibrium solidifcation process. The quasicrystalline materials can be synthesized by mechanical alloying, which is a solid state powder processing technique involving repeated cold welding, mechanically activated interdiffusion, fragmentation and dynamic recrystallization of powder particles in a high energy ball mill, is an ideal processing route to develop nanoquasicrystalline materials at ambient temperature. 14,15 Quasicrystal Quasicrystal phases are a novel class of intermetallics compou- nds that exhibit conventionally forbidden rotational symmetries in their diffraction patterns, which are incompatible with translational periodicity. 16 The breakthrough on rapidly solidifed Al–14% Mn alloys have created new concepts of ordered but no periodic atomic arrangements which exhibit sharp diffraction peaks with icoshahe- dral symmetry (m 35). For which he was awarded the Nobel Prize in Chemistry in 2011. Using transmission electron microscopy and associated high–energy electron diffraction, Shechtman made the key observation that rapidly–quenched Al 86 Mn 14 alloy forms small par- ticles in which the nature and relative orientations of the rotational axes could only be explained with icosahedral symmetry as shown in (Figure 1). Furthermore, Shechtman found that these particles did not exhibit twinning, an effect that can sometimes lead to spurious indications of icosahedral symmetry in crystalline materials, notably gold. The icosahedral point group is incompatible with translational periodicity. The sharpness of the diffraction peaks was explained until this time on the basis of the periodicity of the crystalline materials. The diffraction patterns simulated from these structures are startlin- gly close to those observed for the icosahederal phase and this phase was termed as a quasicrystal. The mathematics of diffraction does not necessarily require periodicity; this was discussed by Mackay befo- re the discovery of quasicrystals. 17 The Mackay extended the idea of Penrose, who had developed a scheme of flling space a periodically by a fnite number of tiles. 18 Mackay constructed the three dimen- sional analogue tiles and stressed their importance in the context of crystallography. A Penrose tiling is a non–periodic tiling generated by and a periodic lay down. The aperiodicity of prototypes implies that a shifted copy of a tiling will never match the original as shown (Figure 1). The tiling uses a pair of rhombuses with equal sides but different angles. Ordinary rhombus–shaped tiles can be used to tile the plane Material Sci & Eng. 2017;1(1):1‒3 1 © 2017 Yadav. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and build upon your work non-commercially. Quasicrystal: a beautiful morphology and diffraction pattern Volume 1 Issue 1 - 2017 Yadav TP Department of Physics, Banaras Hindu University, India Correspondence: Yadav TP, Department of Physics, Institute of Science, Hydrogen Energy Centre, Centre of Advanced Study, Banaras Hindu University,Varanasi–221005, India, Tel 91–542– 2307307, Fax 91–542–2368468, Email yadavtp@gmail.com Received: February 13, 2017 | Published: April 19, 2017 Abstract The synthesis of quasicrystalline phases in complex metallic alloys appears to be advantageous for fundamental research as well as practical application. Studies on quasicrystals and their applications have been research frontiers in chemistry, physics, mathematics, materials science and metallurgy in the past few decades. The remarkable progress has been made in the formation, growth and phase stability, structure and modeling, mathematics of quasiperiodic and a periodic structures, physical properties (transport, magnetic, dynamical, mechanical etc.), surfaces and over layers, applications etc. However, the structural solution of the quasicrystal is still under debate and it will provide a broad aspect for future development and guide the investigations of different aspects of quasicrystals. Therefore, a review on the quasicrystal may be attractive for material science & engineering community. Keywords: intermetallic, nanostructured, quasicrystal, mechanical, alloying/ milling, rapid solidification Material Science & Engineering International Journal Mini Review Open Access