Deformation behavior of heterogeneous lamellar Cu-Fe-P immiscible alloys with enhanced strength and ductility produced by laser powder bed fusion

Cu-Fe-P immiscible alloys characterized by heterogeneous lamellar structure were manufactured by laser powder bed fusion (LPBF) and the deformation behavior of LPBF-produced immiscible alloys was investigated systematically. When the linear energy density of 133 J/m is adopted during LPBF, the immiscible alloy exhibits the highest compressive strength (∼1 GPa) and engineering strain (∼27%). The high strength of the LPBF-produced immiscible alloy is attributed to the heterogeneous lamellar structure including the interconnected Fe₂P layer and nano-Fe₂P particles as “hard” phase dispersed in the ε-Cu matrix as the “soft” phase. Moreover, the good ductility is attributed to the fine ε-Cu grains as “soft” phase precipitated within the lamellar Fe₂P due to the secondary liquid phase separation (SLPS). This “soft-hard-soft” heterogeneous microstructure can effectively delay crack growth to exhibit excellent mechanical properties in the LPBF-produced immiscible alloys.