Triple the ductility of as-cast Al–Si alloys by phase-selective recrystallization

Very recently, a method of phase-selective recrystallization has been proposed to significantly increase the ductility of eutectic alloys. Different from the conventional methods, such as adding modifiers and severe plastic deformation, phase-selective recrystallization is a simple way to control the microstructures with selective recrystallization of the soft phase but refining the hard phase. In this paper, we reveal the microstructure evolution in the phase-selective recrystallization treatment of Al–Si alloys. The results show that through phase-selective recrystallization, the microstructure of the eutectic Si phase with high degree of spheroidization and fine grains of the α-Al matrix can be obtained. Simultaneously, the refined hard Si particles and the soft α-Al grains brought the unusual tensile elongation of 24%, triple of that in as-cast state. Meanwhile, the ultimate tensile strength increased from 208 MPa to 291 MPa. The performance of Al–Si alloy with phase-selective recrystallization is superior to all previous treatments and can be used to produce high performance Al–Si alloy sheet with large scale.