Effects of the microstructure and texture characteristics on mechanical properties of the Al–Ni–Cu–Fe alloy manufactured by laser powder bed fusion

Abstract

In this study, the Al–Ni–Cu–Fe alloy was fabricated using laser powder bed fusion (LPBF), with controlled Fe content, to investigate its metallurgical effects. Furthermore, the microstructural differences between the coarse-grained (CG), fine-grained (FG) regions, and the melt pool boundary were compared. The results showed that the FG region exhibited grain-boundary and precipitation strengthening effects. The grain orientation in the FG region was randomly distributed, leading to the randomly oriented columnar grains with a small ratio of low-angle misorientations in the CG region. This prevented the CG region from developing a temperature gradient texture and provided a solid foundation for the high strength. Both high (Al–4Ni–2Cu–1.4Fe) and low (Al–4Ni–2Cu–0.7Fe) Fe-addition alloys exhibited strengths of over 600 MPa. The FG region of the 1.4Fe contained more strengthening phases, contributing to its higher strength. However, the presence of more incoherent interfaces between Al9FeNi and the α-Al lattice resulted in reduced ductility. On the other hand, the 0.7Fe alloy exhibited lower brittleness and improved ductility. Overall, the LPBF Al–Ni–Cu–Fe alloy shows promising potential for aerospace applications, and a comprehensive understanding of the strengthening mechanisms and microstructure can expand its application scope.

Keywords

• Laser powder bed fusion (LPBF)
• Al–Ni–Fe alloy
• Precipitation
• Texture
• Al9FeNi