Multi-principal element grain boundaries: Stabilizing nanocrystalline grains with thick amorphous complexions

Amorphous complexions have recently been demonstrated to simultaneously enhance the ductility and stability of certain nanocrystalline alloys. In this study, three quinary alloys (Cu–Zr–Hf–Mo–Nb, Cu–Zr–Hf–Nb–Ti, Cu–Zr–Hf–Mo–W) are studied test hypothesis that increasing chemical complexity grain boundaries will result in thicker amorphous further stabilize a microstructure. Significant boundary segregation Zr, Nb, Ti is observed Cu–Zr–Hf–Nb–Ti alloy, which creates quaternary interfacial composition limits average size 63 nm even after 1 week at ~ 97% melting temperature. This high level thermal attributed complex chemistry structure resulting from multi-component segregation. High-resolution transmission electron microscopy reveals increased region alloy results an complexion thickness 2.44 nm, approximately 44% 32% than previously Cu–Zr Cu–Zr–Hf alloys.Graphical abstract