Crystallographic features of iron-rich nanoparticles in cast Cu–10Sn–2Zn–1.5Fe–0.5Co alloy

• Iron-rich nanoparticles in cast Cu–10Sn–2Zn-1.5Fe-0.5Co (wt.%) alloy were clearly identified by Cs-corrected STEM.
• Several distinctive crystal structures and orientation relationships (OR) of iron-rich nanoparticles were identified.
• The characteristic (3̅11̅)Cu facet plane was observed in the Kurdjumov-Sachs (K-S) nanoparticles.
• Ear-like iron-rich nanoparticles exhibiting a preferred orientation on the {200}γ-Fe planes were presented.

The crystallographic features of iron-rich nanoparticles in Cu–10Sn–2Zn–1.5Fe–0.5Co (wt.%) alloy fabricated by centrifugal casting were investigated. Near-spherical and ear-like iron-rich nanoparticles were both observed. Analysis of electron diffraction patterns and Moiré fringes of iron-rich nanoparticles showed the coexistence of several crystal structures and orientation relationships (OR). Most of the near-spherical nanoparticles with 2–20 nm in diameter possess face-centered cubic (f.c.c.) structure with cube-on-cube OR with Cu matrix. The near-spherical nanoparticles (2–20 nm) possessing body-centered cubic (b.c.c.) structure with Kurdjumov–Sachs (K–S) OR also exist. Moiré fringes were observed in such nanoparticle, which exhibits the (3̅11̅)Cu facet plane contrary to the previous research. Ordered b.c.c. iron-rich nanoparticle with Nishiyama–Wassermann (N–W) OR characterized by a periodic array of distinguished striations perpendicular to the [1̅10]Cu direction was detected. Ear-like iron-rich nanoparticles (20–150 nm) were identified as f.c.c structure. Furthermore, the formation mechanism of ear-like iron-rich nanoparticle was elucidated.