Calorimetric Studies of Precipitation and Dissolution Kinetics in Aluminum Alloys 2219 and 7075

摘要: Differential scanning calorimetry (DSC) was used to study the kinetics of precipitation and dissolution metastable stable phases in aluminum alloys 2219 7075. A comparison DSC scans obtained at heating rates 1, 5, 10, 20 K per minute showed that, during a scan, θ′ θ η′ η 7075 were limited by their reaction kinetics. Likewise, GP zones, η′, found be dominated In contrast, thermodynamic equilibrium between these matrix. Analysis kinetically peaks dependence on rate particle size that zone could best described three-dimensional volume diffusion expression with an activation energy equal for diffusion. The formation Avrami withn = 1.1, indicating nucleation not controlling step. pronounced prior plastic deformation observed ascribed influence matrix dislocation density diffusivity.