Formation of Cu_2FeAl_7 phase in friction-stir-welded SiCp/Al-Cu-Mg composite

摘要

Extruded 15 vol. percent SiCp/Al-Cu-Mg composite was friction-stir-welded (FSW) and subjected to subsequent post-weld T4-treat-ment. The formation of Cu_2FeAl_7 phase with Fe resulting from steel tool wear was identified at or near the SiC particle interfaces by using transmission electron microscopy, high-resolution electron microscopy and differential scanning calorimetry. Two types of Cu_2FeAl_7 phases were observed: a single crystal phase and a polycrystalline nanostructured phase. No elemental iron was detected. The formation mechanism of the Cu_2FeAl_7 phase is discussed.