X-ray diffraction studies of the liquid and melt-spun Al–Co–Si alloys

•We have investigated the liquid and melt-spun Al–Co–Si alloys.•The phase CoSi is forming at fast cooling of Al74Co14Si12 melt.•The short-range order of the liquid Al–Co–Si and Al–Co alloys has much in common.•Increasing of Si content causes the formation of polytetrahedral clusters.

The short-range order in the liquid Al86 − xCo14Six (x = 4, 10, 12 at.%) alloys at 50, 150 and 250 °C above liquidus temperature has been studied by X-ray diffraction and reverse Monte Carlo simulations. The analysis of local atomic structure in RMC-models has been carried out by means of the Voronoi–Delaunay method. The existence of a prepeak on the total structure factor curves of the liquid alloys that identified medium range order caused by the specific arrangement of Co atoms has been observed. It was discovered that metastable CoSi intermetallic and nanocrystalline Al and Si phases have been formed in melt-spun Al74Co14Si12 alloy. The annealing of the melt-spun Al74Co14Si12 ribbons causes the attainment of Al9Co2 and Si crystal phases.