Dynamic softening behavior in an Al12Si3Cu0.04Sr alloy during thermal deformation: Role of Si particle-dislocation interactions

Abstract

Thermal compression tests (300–450 °C, 0.001–1 s⁻¹) were conducted to analyze an Al12Si3Cu0.04Sr alloy's thermal deformation behavior. Based on the mechanical characteristics, the strain rate sensitivity index was determined. The Arrhenius constitutive equation was established based on the peak stress, and a hot processing map integrating four instability criteria (Gegel, Malas, Prasad, Murty) was developed. Using electron backscattered diffraction (EBSD), we analyzed the microstructural evolution and dynamic softening mechanisms. The results revealed the role of Si phases in dynamic softening and the strain-rate-controlled dynamic recrystallization mechanism. It was found that Si particles promote the dynamic recrystallization of the alloy; especially at higher strain rates, the deformation mechanism of the alloy tends to transition from dynamic softening to dynamic recrystallization.