Abstract
In the present study, the different approach of metal reinforcement particles addition was studied. Aluminum matrix composite (AMC) with 5 % alumina (α-Al₂O₃) reinforcement was prepared via stir casting method, using various casting temperature, stirring speed, and stirring time. As a source of reinforcement, alumina master alloy with a high concentration of alumina particles (50 %) prepared through gas pressure assisted infiltration (GPAI) was distributed during stirring. Distribution of the particles and structural characterization dependence on processing parameters were examined. Electron microscopy (SEM, TEM) was used for complex visual investigation of the distribution of dispersed particles and to quantify the degree of disintegration of the alumina master alloy after the casting process. To show the effect of the uniformity of the particle distribution on mechanical properties, uniaxial tests were performed after extrusion. Results show an increase in strength of the stir cast composites is in agreement with the particle distribution measurement (cluster size). The highest UTS values are achieved for composites with the lowest values of the remaining clusters.

Key words
aluminum matrix composite, α-Al₂O₃, alumina master alloy, stir casting, particle distribution

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