Ultrastrong and ductile precipitation-hardened alloy via high antiphase boundary energy

Coherent precipitation-hardened alloys often struggle to achieve both ultrahigh strength and exceptional ductility due to their limited resistance to dislocation motion and vulnerability to glide plane softening. Here, we tackle these challenges by introducing multicomponent precipitates with much increased antiphase boundary (APB) energy. In a model Ni$_3$Al-type (L1$_2$) precipitation-hardened face-centered cubic (FCC) NiCo-based alloy, we incorporate multiple elements at the Al sublattice sites within the precipitates, reducing antisite defects and enhancing ordering degree. This process yields multicomponent precipitates with an ultrahigh APB energy (~308 ± 14 millijoules per square meter), which notably strengthens the alloy. Moreover, the exceptionally high APB energy transforms the deformation mechanism from dislocation shearing to stacking fault shearing, thereby avoiding glide plane softening. These result in a tensile yield strength of 1616 ± 9 megapascals, an ultimate tensile strength of 2155 ± 22 megapascals, and a uniform elongation of 10.1 ± 0.3% for the alloy.