Al–FeAl–TiAl–Al 2O 3 composite with hybrid reinforcement

Abstract

The process of obtaining cast aluminium composite of dispersive structure and hybrid reinforcement has been presented in the article. An Aluminium alloy (AlMg 2) was modified with a powder mixture which, when in reaction with aluminium, reinforced the matrix with intermetallic phases and aluminium oxide. According to the technological conception, an assumption was made, that the cast composites would be produced in technological procedure shown in Fig. 1. The reinforcing phases were using Fe–Ti–Al powder mixtures with aluminium oxide formed in a self-propagating high-temperature synthesis (SHS). The structure and phase composition of the composite powder used for the matrix alloy modification are shown in Fig. 2. A composite alloy Al–FeAl–TiAl–Al 2O 3 was produced by casting method (gravity casting, mechanical mixing) after which its structure was determined. It was assumed that the final product of the applied production process will be an aluminium composite with hybrid reinforcement, consisting of Fe–Al and Ti–Al intermetallic phases and aluminium oxides. Optical microscopy, electron scanning microscopy and X-ray phase analysis were used to characterize the microstructure of the composites produced. Presence of aluminium, Al 3Ti and Al 13Fe 4 phases and dispersed Al 2O 3 was confirmed in the composite by XRD method. The dispersion structure and phase composition of the composites are presented in Figs. 3–6. The composites formed in an in situ reaction constitute a newer generation of casts, in which dispersion reinforcement is obtained in the form of intermetallic and ceramic phases coherent with the matrix, very often below 1 μm in size. The designed process allows for the structure modification of the applied casting aluminium alloys in different technological variants.