| Two alloys, Al-2% Si and Al-2% Si-0.25% Sc, were subjected to equal-channel angular pressing (ECAP) up to a maximum of 4 passes using route Bc at room temperature. This processing gave ultrafine-grained microstructures with grain sizes of ~0.70 µm without Sc and ~0.30 µm with the 0.25% Sc addition. The improvement in the mechanical properties of the Al-2% Si alloy due to the Sc addition was studied using a ball-indentation technique (BIT). These tests showed that the addition of 0.25% Sc decreased the grain size of the Al-2% Si alloy in the cast condition from 40 to 25 µm with an increase in the ultimate tensile strength (UTS) from ~106 to ~185 MPa. In addition, ECAP of the Al-2% Si-0.25% Sc alloy gave a UTS of ~355 MPa which was ~30% higher than the Al-2% Si alloy without the Sc addition. This increase is due to the presence of fine Al3Sc precipitates. |
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