Dynamic Recrystallization Behavior and Critical Conditions of SiC_p/A1-Cu Composite

Abstract

Using the Gleeble-1500D simulator, the high temperature plastic deformation behavior of 40%SiCP/Al-Cu composite were investigated at 350-500℃ with the strain rate of 0.01-10 s-1. The stress-strain curves were obtained during the tests. The critical conditions of dynamic recrystallization for onset of DRX during deformation of 40%SiCP/Al-Cu composite was obtained by computation of the strain hardening rate (θ) from initial stress-strain data and introduction of the inflection point criterion of ln θ-ε curves and the minimum value criterion of (-∂(ln θ)/∂ε)-ε) curves. The results indicate that the softening mechanism of the dynamic recrystallization is a feature of high-temperature flow stress strain curves of the composites, and the peak stress increases with the decrease of deformation temperature or the increase of strain rate. The inflection point in the ln θ-ε curve appears, and the minimum value of the (-∂(ln θ)/∂ε)-ε) curve is presented when the critical state is attained for this composite. The critical strain decreases with the decrease of strain rate and the increase of deformation temperature. There is linear relationship between critical strain and peak strain, i.e. εc=0.528εp. The predicting model of critical strain is described by the function of εc=4.58×10-3Z0.09. Electron microscopic analysis show that the dynamic recrystallization occurs when the strain is 0.06 (T=400℃, ε=10 s-1), and the dynamic recrystallization grains fully grow up when the strain is 0.2.

Keywords

• SiC_P/Al-Cu composite
• hot deformation
• strain hardening rate
• dynamic recrystallization
• critical condition
• microstructure