ABSTRACT Aluminum has found many engineering applications due to its great formability, low density, and high resistance to corrosion. Since aluminum is not very strong compared to other structural materials, it is usually strengthened by introducing a second phase, reinforcing particles or fibers. The first aim of this work is to strengthen aluminum using powder technology. Yttria is selected as reinforcing particles. It is demonstrated that by adding yttria particles (3, 5, 7, and 10wt% with particles size 5.54 ?m as reinforcing phase, aluminum can be strengthened and the microstructure of aluminum becomes finer with an increase in yttria content. The second aim of the present work is to improve the erosion-corrosion behavior of aluminum metal matrix composite. An erosion-corrosion test for the prepared composite was carried out in slurry solution (1wt%SiO2 sand in 3.5wt% NaCl solution as the erodent) with impact angles (90°). Comparing with the base aluminum sample, Brinell hardness was increased by (83%) while erosion-corrosion rate decreased by (91%) for the best sample which contained (10 wt.%) Y2O3 The improved properties of aluminum by the yttria addition may thus be attributed to residual yttrium in the Al matrix, and the resultant finer microstructure.
CONCLUSIONS
1. Powder metallurgy is an effective method in manufacturing metals matrix composite, where the optical microscope images show a uniform distribution of Y2O3 particles in the aluminum matrix.
2. Brinell hardness is increased with the addition of Y2O3 particles by 11%, 20%, 26%, and 83% for samples of (3wt.%), (5 wt.%), (7 wt.%), and (10 wt.%) Y2O3 respectively.
3. Erosion –corrosion rate in slurry solution (1 wt.% SiO2) in 3.5 %NaCl is decreased with addition of Y2O3 particles by 15%, 47%, 76%, and 91% for samples of (3 wt.%), (5 wt.%), (7 wt.%), and (10 wt.%) Y2O3 respectively under same conditions
4. In erosive–corrosive media the removal of material is due to the combined effect of erosion and corrosion and hence erosion-corrosion rate is significantly higher.
5. LOM images of damaged surfaces of composites showed that the damage mechanism is dominated by plugging and indentation.
6. Experimental densities are increased gradually with the addition of Y2O3 particles by (4%), (8%), (11.5%), and (21%) for samples of (3 wt.%), (5 wt.%), (7 wt.%), and (10 wt.%) Y2O3 respectively
7. Sample of (10 wt.%) Y2O3 has the best combination of properties. It has low weight and low porosity and good hardness and good erosion-corrosion resistance that makes it eligible for use in many engineering applications.