Dissolution behavior of nano-sized precipitates in aged Al-Si-Mg-Cu alloy during cold deformation

Abstract

Dissolution of precipitates is an important phenomenon during the cold deformation of aged Al-Si-Mg-Cu alloys, which significantly affects the alloy’s mechanical and conductive behavior. Here, we reveal its mechanism via nanometer scale observation on the microstructural evolution of a representative Al-Si-Mg-Cu aluminum alloy. The accumulation of dislocations led to micro tensile stress from both ends to the middle of the precipitates, and caused the precipitates sequentially to transform into smaller particles, Guinier-Preston zones and solute atoms. The increasing number density of fractured precipitates and the cumulative lattice adsorption energy are the major driven force of the dissolution process. These findings are crucial for laying down the thermomechanical treating technology of such alloys to improve their mechanical and conductive performance.