Structure-property models in Al-Zn-Mg-Cu alloys: A critical experimental assessment of shape castings

The applicability of existing process models to predict the total yield strength of Al-Zn-Mg-(Cu) wrought alloys was investigated with the aid of our experimental results that were obtained for the cast components of these alloys. The cast specimens were prepared using a new process known as the Controlled Diffusion Solidification (CDS) technology. Three distinctive compositions from the realm of Al-7000 alloy family were selected with a sum total alloying elements (Zn + Mg + Cu) of 4.3, 7.7 and 10.6 wt%. The validation assessment of the predictive models was conducted using a comprehensive analysis that correlated the experimental micro-structural parameters to the uniaxial tensile properties of these alloys. The evaluation analysis has lead to a selection of the most influential strengthening components to the total yield strengths in these alloys; which were obtained independently from the original base models. As a result, a consolidated model is proposed with an over-all accuracy of three times the maximum standard deviation ( ± 3Sd) of the experimental tensile results. In an earlier publication, the experimental results for the micro-structural parameters and uniaxial tensile results that used here in this study were obtained and discussed by using a quantitative metallography and image analyses on the SEM and TEM micrographs.