Morphological and structural studies on Al reinforced by Al2O3 via mechanical alloying

• Al matrix composite was produced in a planetary ball mill by granular aluminum.
• High amounts of alumina powder as reinforcements were used.
• Effect of milling on unreinforced and reinforced Al powder was studied.
• Three different steps of mechanical alloying were recognizable.
• Addition of reinforcements to the system accelerated the alloying process.

In the present work, aluminum matrix composite (Al–Al2O3) was produced using mechanical alloying in a planetary ball mill. Aluminum granular in size (1–3 mm) with high amount of alumina particles (x50 = 7.6 μμm) were milled up to 500 minutes in a planetary ball mill to indicate the effect of hard particles on the alloying acceleration. The results revealed that high amount of alumina particles promoted the work hardening and decreased the time of mechanical alloying. Further, the particle size analysis indicated that prolonging the milling time caused the particle size to drop from an initial value of 1–3 mm to about 10 μμm during the milling. The X-ray diffraction results demonstrated a continuous decrease in crystallite size in Al phase from 350 to 60 nm. Hardness tests illustrated that hardness increased as a function of milling time. The results verified that the produced composites have a homogeneous distribution of alumina particles in the aluminum matrix. The results showed that the aluminum matrix composite can be produced from the granular Al (mm in size) with micron sized Al2O3 by mechanical alloying process.

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