Synthesis And Characterization Of Intermetallic Compounds In Al-Fe And Al-Mn-Si Quasicrystalline System

A series of complex intermetallic compounds of two quasicrystal systems of Al-Fe and Al-Mn-Si were synthesized by high-pressure sintering and spark plasma sintering methods in the present work.The crystal structures of some precipitates were analyzed and refined by single crystal X-ray diffraction techniques.The mechanical stability,kinetic stability and thermodynamic stability of the new phase in Al-Fe system were studied by first-principles calculations.Meanwhile,the related properties of energy band structure,density of states and electronic local function were analyzed.Furthermore,the intrinsic building units of Al₃?Mn,Si?phase in Al-Mn-Si system were analyzed by the topological methods.Firstly,in the Al-Fe high-pressure sintering sample with atomic ratio of 3:1,a new Al₁₃Fe₃ phase was found and determined as a trigonal phase.The unit cell parameters are:a=14.5906?8??,b=14.5906?8??,c=7.7002?4??,?=?=90°,?=120°,and the space group is R3c.First-principles calculation results reveal that the phase was a metallic stable phase.Secondly,an Al-Fe phase of exactly atomic ratio 3:1 was found in the precipitate of Al₂₊?Fe??=0.67?by spark plasma sintering and its crystal structure was determined.The unit cell parameters are:a=7.6474?7??,b=6.4097?6??,c=4.2114?4??,?=?=?=90°,space group is Cmcm.The ordered crystal structure was optimized by first-principles calculations and its stability,related electrical properties and bonding conditions have been investigated.Finally,in the educts of the Al₇₄Mn₂₀Si₆ quasicrystal system by spark plasma sintering,a new Al_4.24MnSi_0.47 phase with space group Im-3 was found and its unit cell parameters are:a=b=c=12.632?4??,?=?=?=90°.The topological feature of the new phase was analyzed using the"nano cluster"algorithm integrated in the ToposPro software.