Solid solution softening of Ti₂AlC induced by alloying of boron

Solid solution softening is an unusual adjustment behavior that is attractive for material strength. In this paper, the effect of boron alloying on the strength of Ti₂AlC is investigated by first-principles calculations. Our results show that the elastic modulus and ideal strength of Ti₂AlC decrease overall due to alloying with boron, which indicates that solid solution softening occurs. Conversely, ductility and plasticity of Ti₂AlC are greatly enhanced by alloying with boron. This phenomenon in Ti₂AlC is mainly related to the reduction of Peierls stress and generalized stacking fault energies caused by alloying with boron. Our work provides an ideal candidate platform to study the solid solution softening effect in ceramics and provides theoretical guidance for engineering applications of MAX phase materials.