Evolution of iron-rich intermetallics and elevated temperature mechanical properties in gravity die cast 2A16 Al alloy

ABSTRACT

The evolution of iron-rich intermetallics and the mechanical properties at elevated temperature in gravity die cast 2A16 alloys with a high Fe content of 0.5 wt-% were investigated using SEM, TEM, deep etching technique, and tensile test. The results showed that the Chinese script-like α-Fe transforms to the β-Fe phase during T7 heat treatment. The newly formed β-Fe with a cylindrical shape minimised their surface area. A nano sized α-Fe dispersoid was found in the α (Al) matrix in Al–Cu alloys with high Fe content during T7 heat treatment. At the elevated temperature of 573 K, the 2A16 alloys with high Fe content of 0.5 wt-% showed superior tensile properties compared to those of the commercial aluminum alloys, and this is attributed to the prevention of grain boundary sliding resulting from the presence of β-Fe and the long term thermal stability of nanosized α-Fe dispersoids in the α (Al) matrix.

KEYWORDS:

• Al–Cu alloys
• heat treatment
• iron–rich intermetallic
• elevated temperature mechanical properties