Effects of Y2O3 on the hot deformation behavior and microstructure evolution of Al2O3-cu/35Cr3TiB2 electrical contact composites

Abstract

The Al2O3-Cu/35Cr3TiB2 and 0.5Y2O3/Al2O3-Cu/35Cr3TiB2 composites were prepared by a combination of fast hot compression sintering and internal oxidization. The effects of Y2O3 on the hot deformation behavior and microstructure evolution of the composites were investigated. According to the hot deformation data, the constitutive equations, hot processing maps, and critical dynamic recrystallization models were constructed for the two composites. The Y2O3 addition enhanced the flow stress, activation energy, and hot processing properties of the composites. This led to a reduction in the percentage of dynamic recrystallization structure from 25.3% to 19.4%, and decreased the amount of high-angle grain boundaries from 77.8% to 71.4%. Y2O3 was distributed at grain boundaries and phase interfaces, effectively impeding dislocation movement and grain boundary migration. Notably, the strain distribution within Y2O3 exhibited greater homogeneity compared to the Cu matrix. More twins and stacking faults were observed inside the 0.5Y2O3/Al2O3-Cu/35Cr3TiB2 composites, which synergistically strengthened the matrix.