Mechanical properties of directionally solidified Al--Si eutectic

Technical Report · Sun May 01 04:00:00 EDT 1977

DOI:https://doi.org/10.2172/7317222· OSTI ID:7317222

Morrow, D G

The effect of directional solidification on the yield strength of the Al-Si eutectic alloy has been studied. Eutectic alloys (Al-12.7 wt. % Si) were directionally frozen at growth rates, R, between 0.097 cm/h and 47.0 cm/h through a temperature gradient of about 80/sup 0/C/cm. As found by Day and Hellawell, an oriented (001) Si fiber texture is obtained for rates less than 1.0 cm/hr, and at higher growth rates microstructures similar to the as-cast eutectic are found. At the lower growth rates, banded structures alternating rich in Si and lean in Si were also observed. Tensile measurements indicated that the yield strength is independent of R at growth rates less than ca. 1.0 cm/h, while at higher growth rates the strength increases linearly with R/sup 1/4/. Composite strengthening due to aligned Si microstructure at low R was not exhibited due to the preferential yielding within the banded structures. Yield strengths for higher growth rates are controlled by a precipitate spacing effect.

• Research Organization: California Univ., Berkeley (USA). Lawrence Berkeley Lab.
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 7317222
• Report Number(s): LBL-6036
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
ALLOY SYSTEMS
ALLOYS
ALUMINIUM ALLOYS
ALUMINIUM BASE ALLOYS
BINARY ALLOY SYSTEMS
CRYSTAL GROWTH
CRYSTAL STRUCTURE
GRAIN ORIENTATION
MECHANICAL PROPERTIES
MICROSTRUCTURE
ORIENTATION
SILICON ALLOYS
TENSILE PROPERTIES
YIELD STRENGTH