Microstructure analysis of high-temperature deformation of Al-Cu alloy

Abstract

An isothermal compression test of Al-Cu alloy at a high temperature is carried out, with a thermal compression strain rate of 1 s−1 in a thermal deformation temperature range of 500 °C∼800 °C. Its thermal vacuum stress-strain curve shows that process hardening dominates the compression process, and is accompanied by weak dynamic recrystallization (DRX) effect. No obvious peaks of recrystallization are observed. Electron back-Scattered diffraction is used to analyze the high-temperature deformation and microstructure characteristics in different locations of this alloy. The results show that: sizes of crystal grains grow slowly as temperature rises, and the deformation of crystal grains is the primary factor that drives the compression deformation. DRX nucleation grows slowly. The Schmid factor of deformed crystal grains and recrystallized grains rises from 8.97 to 10.08. As for some of the slightly deformed crystal grains, this factor is only 1.88 at most. Crystal grains experience the largest deformation at 600 °C, accompanied by strong fiber textures. At each temperature, low-angle grain boundaries (LAGBs) are dominant at first, but they gradually transform into high-angle grain boundaries (HAGBs). Meanwhile, Σ CSL grain boundaries slowly transform to Σ3 grain boundaries with the proportion rising from 2.6% to 6.2%.