Achieving Strength-Ductility Synergy via Huge Lüders-Type Deformation

This study presents a strategy to achieve strength-ductility synergy by introducing huge Lüders-type deformation in ultrafine grained alloys. The Lüders-type deformation occurs at a temperature range when the critical stress of deformation twinning is close to that of dislocation slip, which allows the mutual promotion between deformation twinning and dislocation slip and thus induces the band formation. The strategy was verified in a NiTiNbFe alloy which exhibited a ~50% Lüders-type strain and 1090 MPa strength when deformed at -50 ℃. This property is superb than those deformed at other temperatures.