Eutectoid transformation in Cu-Be alloys tuned by cooling pathways: from crystallography to mechanical properties

• • Two-step homogenization eliminates dendritic segregation and suppresses acicular phase formation, enabling reliable processing of Cu-2.8Be and Cu-3.8Be alloys. • • β → γ transformation involves isotropic contraction of ~3.9%, yielding lower strain energy than anisotropic β → α (expansion ~28.5%, contraction ~9.2%), explaining preferential γ nucleation. • • Rapid cooling yields incomplete eutectoid decomposition with α/γ lamellae interlamellar spacing down to ~7 nm, enhancing strength but introducing high lattice strain (ε_xx=0.0167, ε_yy=0.0095) at interfaces. • • Mechanical incompatibility and internal strain at α/γ interfaces promote stress concentration and crack initiation, limiting ductility; controlled cooling paths are critical for balancing strength and formability.