Overcoming the strength-ductility trade-off in CoNi-based alloy via alloying of Mo and AlTiMo

Alloying is a vital strategy to tune mechanical behaviours and deformation mechanisms of metals to achieve excellent strength-ductility synergy. In this study, we combined solid-solution and grain boundary strengthening, and enhancing work-hardening via tailoring deformation mechanism, to overcome strength-ductility trade-off for the CoNi-based alloys. The addition of Mo or AlTiMo not only improves efficiently the strength with notable solid-solution and grain-boundary strengthening effect, but also enhances significantly the work-hardening capability. For example, adding 7 at. % Mo to the CoNi alloy leads to the yield strength increased by 116 %–411 MPa and no loss in ductility. The combined addition of (Al + Ti) and Mo intensively increases the yield strength by 160 %–∼500 MPa, along with excellent ductility beyond 70 %. The alloying of Mo and AlTiMo overcomes the strength-ductility trade-off dilemma, which is associated with the change of deformation mechanisms. These findings would open a new door for the future development of the Mo/AlTiMo-contained CoNi-based alloys with excellent ductility.