Promoting dynamic precipitation of Mg-Bi-Al alloy during extrusion via introducing heterogeneous particles

A novel strategy of introducing heterogeneous particles to promote dynamic precipitation is proposed for designing Mg-Bi alloys with high strength and excellent ductility. Through in-situ formation and extrusion, uniformly distributed trace Mg2Si particles are successfully obtained in the Mg-5Bi-3Al-0.4Si alloy. This significantly improves precipitation characteristics of nano Mg3Bi2 phases, as evidenced by reduced size and increased number density. Consequently, the Mg-5Bi-3Al-0.4Si alloy exhibits an increase in yield strength of 42 MPa, up to 371 MPa. Remarkably, introducing trace particles does not damage ductility, primarily due to the activation of non-basal slip and suppressed intergranular fracture tendency.