Metalurgi serbuk adalah salah satu cara untuk pembentukan komposit matrik logam aluminium. Meterial yang digunakan dalam penelitian ini adalah serbuk paduan Al-Si sebagai matrik dan serbuk Al2O3 sebagai penguat. Serbuk paduan Al-Si berukuran 53 –210 μm dengan bentuk partikel tidak beraturan yang diperoleh dengan cara pengikiran. Al2O3 serbuk yang digunakan dengan ukuran partikel 63 –200 μm produksi Merck Jerman. Variasi penambahan Al2O3 adalah 0, 3, 6, 9, 12 dan 15% berat. Pembentukan spesimen dengan variasi tekanan kompaksi 300, 400, dan 500 MPa, suhu sinter 550 oC selama 2 jam dalam lingkungan gas argon. Pengujian sifat fisis meliputi pengukuran densitas relatif dan pengamatan struktur mikro dengan mikroskop optik dan SEM. Pengujian sifat mekanis meliputi kekerasan Vickers, kekuatan bending, keausan dan pengujian tegangan radial pada bushing. Hasil penelitian menunjukkan bahwa dengan meningkatnya tekanan kompaksi meningkatkan densitas, kekerasan dan kekuatan bending dari komposit paduan Al-Si/Al2O3. Sedang penambahan Al2O3 menurunkan densitasnya. Peningkatan sifat mekanis yang optimal diperoleh pada komposit dengan kandungan 6% berat Al2O3 dengan tekanan kompakasi 500 MPa

Powder metallurgy is known as a method to produce aluminum metal matrix composites. The materials used in this research were Al-Si alloy powder as the matrix and Al2O3 powder as the reinforcement. The Al-Si alloy powder with irregular shape and particle size of 53 –210 μm was produced by mechanical grinding method. Al2O3 powder with particle size 63 –200 μm was supplied by Merck Germany. The various content of reinforcement were 0, 3, 6, 9, 12 and 15% weight of Al2O3. Each composition was compacted at various pressures of 300, 400, and 500 MPa to produced green bodies. The green bodies were then sintered at 550 oC for 2 hour in argon atmosphere. Density of specimens was measured using Archimedes method. Optical and Scanning Electron Microscope were used to observe the microstructures. Mechanical properties of the specimens including Vickers hardness, modulus of rupture, wear resistance and radial strength of bushing components was also tested. The results of the research show that relative density, Vickers hardness and modulus of rupture of composites increases with increasing compacting pressure. However relative density decreases with increasing of Al2O3 content. The optimum mechanical properties were achieved on the composites containing 6% weight of Al2O3 with compacting pressure of 500 MPa. Keywords: Al-Si alloy/Al2O3 composites, powder metallurgy, compacting pressure.