Hot deformation behavior and microstructure of Ni-Cu rich Al-Si AA4032 alloy

Abstract

The Al-Si alloy family is among the most widely used nonferrous alloys, in both cast and wrought products. The alloys have undergone a continuous progress toward improvement of various properties. The present research investigated the hot deformation behavior of AA4032 alloy, modified with addition of 3.5 %wt of Ni and 3%wt of Cu. The study was carried out using constitutive equations at the temperature range of 693–823 K (420–550 °C) alongside the strain rates of 0.001–1 s−1. The processing maps were determined by superimposing the instability maps on power dissipation maps. Moreover, the effect of extra copper and nickel on the microstructure and phase formation was studied via optical microscopy, SEM and TEM. The hot deformation activation energy of the Ni-Cu rich alloy is also calculated to be 338 KJ/mol (at ε = 0.1) which is notably higher than that of the self-diffusion of pure Al. It is found that the best hot working condition is the temperature range of 720–780 K with a strain rate of 0.001–0.03 s−1. The microstructure of the alloy at the calculated safe zone was uniform, while it showed cracking at the unsafe region of deformation parameters.