V-stabilized γ′′ phase: a new pathway to enhanced intermediate-temperature ductility in NiCoCr-based multi-component alloys

Abstract

This work proposes a new design strategy for overcoming the strength-ductility trade-off of γ′′-strengthened multi-component alloys at intermediate-temperatures. By increasing the V content, the alloy’s ductility is enhanced accordingly (650°C tensile-elongation, 9.85%→15.97%) without compromising strength. This enhancement is attributed to the improved stability of γ′′, which results in a suppression of brittle ε lamellae forming at grain boundaries after deformation and a reduction in γ/γ′′ lattice misfit. Concurrently, the increasing V content increases the γ′′ volume fraction, offsetting potential strength loss due to the lattice misfit reduction.

Keywords

• Multi-component alloy
• D022 superlattice
• metastable phases
• precipitation strengthening
• intermediate-temperature ductility