Interfacial structures and grain refinement mechanisms in DED- arc fabricated AlFeCoNiCr/Al-Cu-Mn-Zr composites

• The DED method can add HEAs particles to Al-Cu alloys to prepare composite materials. • HEAs particles can promote the transformation from columnar to equiaxed grains. • HEAs particles can refine the Al-Cu alloys grains by 79.4%. • The addition of HEAs particles to Al-Cu alloys can effectively enhance the strength. In this study, a gravity-fed powder delivery system was used to add high-entropy alloy (HEA) particles to Al-Cu alloys during a directed energy deposition arc (DED-Arc) process. We evaluated the effect of HEA addition on the microstructure, mechanical properties, and porosity defects of the DED-Arc-fabricated Al–Cu alloys. The results showed that HEA particles promoted the formation of intermetallic compounds through interfacial reactions, which significantly enhanced the grain refinement. The yield strength of the as-deposited Al-Cu alloy was 109.3 MPa, which increased to 130.6 MPa after HEA addition, resulting in an improvement of 20.1%. Following the T6 heat treatment, the yield strength of the Al-Cu alloy was 322.1 MPa. In contrast, the HEA-reinforced material exhibited a further increase, reaching 369.3 MPa, i.e., an increase of 14.66%. However, the introduction of HEA particles resulted in an increase in the porosity from 3.2% to 3.67%. In summary, the incorporation of high-entropy alloys has been demonstrated to effectively refine the grain structure and enhance the strength of Al-Cu alloys. However, this process concomitantly increases the porosity. This study offers significant insights into the fabrication of HEA-reinforced aluminum matrix composites using DED-Arc technology, thereby contributing to the advancement of DED-Arc.