Analysis of the η phase of the Al-Cu-Zn system and its relationship with τ' and α phases

In this study, a characterization analysis of a series of Al-Cu-Zn alloys was carried out, focusing on the relationship between the η phase and the surrounding phases. As part of this analysis, the nanohardness of the η phase was measured, along with its average perimeter and the contact perimeter shared with the τ' and α phases—an aspect that has not been previously examined in this type of alloy. In order to accomplish this, the alloys were analyzed using a scanning electron microscope in backscattered electron mode to identify and distinguish each phase. The results demonstrate that a multiple linear regression model, using hardness as the dependent variable and the aforementioned morphological parameters as independent variables, yields a near-zero error. This finding indicates a strong correlation between these variables and both the hardness and the chemical composition of the alloy. The use of phase perimeter as a predictive parameter has not been previously applied to Al-Cu-Zn alloys. Therefore, this study provides a novel methodological contribution, offering a framework that may support the advancement of image analysis techniques in the characterization of multiphase metallic systems.