Development of the high-strength ductile ferritic alloys via regulating the intragranular and grain boundary precipitation of G-phase

•Although the nano-dispersed precipitation of G-phase within the grain hardens the alloy remarkably, its large amount of precipitation at the grain boundary leads to serious alloy embrittlement.•For the first time, the crystal structure transition of nano-dispersed precipitates from the Fe2TiSi-L21 to the Ni16Ti6Si7-G phase is observed within the ferrite at the early stage of aging.•Guided by current TEM and DFT results, the interfacial energy is predicted to play a leading role in forming the cube-on-cube orientation relationship between α-Fe and G-phase.•Adopting the “cold-rolling and aging” process to effectively avoid its precipitation at grain boundaries, a class of high-performance ferroalloys with both high strength and good ductility is realized.