The role of iron in aluminium–silicon alloys is well established, with the element generally regarded as being detrimental to the mechanical properties. However, iron is sometimes unavoidable so we study for the first time, a larger concentration range of iron than has been previously reported, to establish whether the deterioration in mechanical properties is monotonic with concentration. It is found that the variation is not linear, but that the greatest elongation and mechanical resistance is obtained in the presence of 0·4 wt- of iron. The mechanism is attributed to the presence of a particular intermetallic compound that has a Chinese script-like morphology.
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