Effect of Fe-Rich Intermetallics on Tensile Behavior of Al–Cu 206 Cast Alloys at Solid and Near-Solid States
Iron is one of the most common impurity elements in Al–Cu 206 cast alloys as it often causes the precipitation of Fe-rich intermetallic phases during solidification due to its extremely low solid solubility in aluminum. The characteristics of the Fe-rich intermetallics, such as type, morphology, size, and distribution, have significant influences on the tensile behaviors of the Al alloys. In the present work, two Al–Cu 206 cast alloys containing different types of Fe-rich intermetallics (dominated by either platelet β-Fe or Chinese script α-Fe) were cast and their tensile tests were performed at both solid (room temperature) and near-solid (2.8 vol. % liquid) states. It is found that the tensile properties in both solid and near-solid states are improved when the Fe-rich intermetallics change from platelet to Chinese script morphologies. During the solid-state tensile deformation, the failure occurs mainly along the platelet β-Fe intermetallics/Al matrix interface or within the Chinese script α-Fe particles. In the near-solid state, the alloy containing mainly Chinese script α-Fe is found to have more free flow paths for liquid feeding, leading to improved tensile properties. By contrast, the platelet β-Fe can cause the blockage of the liquid flow paths, leading to the degraded tensile properties and worsened susceptibility to hot-tearing.
KeywordsAl–Cu alloy Fe-rich intermetallics Tensile properties Solid and near-solid state Hot-tearing
The authors would like to acknowledge the financial support from the Natural Sciences and Engineering Research Council of Canada (NSERC) and Rio Tinto Aluminum, through the NSERC Industry Research Chair in Metallurgy of Aluminum Transformation at the University of Quebec at Chicoutimi, and support of National Research Council of Canada.
- 1.Liu K, Cao X, Chen XG (2011) Solidification of iron-rich intermetallic phases in Al-4.5Cu-0.3Fe cast alloy. Metall Mater Trans A 42(7):2004–2016Google Scholar
- 5.Seifeddine S, Johansson S, Svensson IL (2008) The influence of cooling rate and manganese content on the β-Al5FeSi phase formation and mechanical properties of Al–Si-based alloys. Mater Sci Eng A 490(1):385–390Google Scholar
- 7.Liu K, Cao X, Chen XG (2013) Formation and phase selection of iron-rich intermetallics in Al-4.6Cu-0.5Fe cast alloys. Metall Mater Trans A 44(2):682–695Google Scholar
- 8.Eskin DG, Katgerman L (2004) Mechanical properties in the semi-solid state and hot tearing of aluminium alloys. Prog Mater Sci 49(5):629–711Google Scholar
- 10.Kamguo Kamga H, Larouche D, Bournane M, Rahem A (2010) Hot tearing of aluminum–copper B206 alloys with iron and silicon additions. Mater Sci Eng A 527(27):7413–7423Google Scholar