Differential Scanning Calorimetry Study of Guinier Preston Zone Formation and Dissolution in 7075 and 7091 Aluminum Alloys

摘要

The aging behavior of P/M 7091 and IM 7075 aluminum were studied by DSC; also hardness and conductivity. The energy associated with the formation and dissolution of Guinier Preston zones is correlated to mechanical and physical properties; equations for conductivity and hardness as a function of heat of reaction are presented. The activation energy fo GP dissolution was established by differential scanning calorimetry (DSC) and values for delta H*, deltaG*, and deltaS* were calculated using absolute reaction rate theory. The activation energy calculated for GP disolution in 7075-T6 is equivalent to the activation energy reported for the diffusion of Zn in aluminum.