The effects of manganese on the Τ-phase and creep resistance in Al-Si-Cu-Mg-Ni alloys

Al7Si0.5Cu0.3Mg(0.3-1)Ni alloys were investigated for elevated temperature performance. It was found that while the yield strength of the overaged alloys at 300 °C increased with Ni, the creep resistance decreased. Microstructural observations revealed that the brittle interdendritic Τ-Al9FeNi intermetallics undergo severe cracking in the early stages of creep deformation, which weakens the interdendritic regions and leads to a decrease in creep resistance. This study shows that Mn additions modify the Τ-phase preventing cracking during creep and increase the creep resistance.