Microstructures and mechanical properties of Al-20Si-xFe (x=3, 5, 7) alloys manufactured by rapid solidification processing

Rapidly solidified Al-20Si-xFe (x=3, 5 and 7 mass%) powders were prepared b y gas atomization. The microstructure consisted of needle shaped delta-Al4F eSi2 particles and primary Si embedded in Al-Si-Fe eutectic. With increasin g Fe content, the size and volume fraction of primary Si decreased. After e xtrusion, the microstructures of the extruded bars showed a homogeneous dis tribution of two different sizes beta-Al5FeSi and Si particles embedded in the cu-Al matrix. By increasing the Fe content from Al-20Si to Al-20Si-7Fe, the ultimate tensile strength (UTS) increased from 215 to 404 MPa at 300 K and from 122 MPa to 240 MPa at 473 K. Of these alloys, Al-20Si-5Fe alloy s howed the best wear resistance. The UTS varied significantly with the initi al powder size but wear resistance was independent of powder size. The effe ct of the particles distributed in the Al matrix upon the UTS was considere d in terms of the cooling rate and particle distribution.