Characterization and Quantification of the Phases Concentration of Cu60–Zn40 Alloy as Candidate Reference Material

This study describes the process of evaluating a commercially available copper–zinc alloy with the goal of creating an internal reference material. The intended use of this candidate reference material is to evaluate the percentage of alpha and beta phases to verify the accuracy in quantifying phase percentages according to the ASTM E562-11 “Standard Test Method for Determining Volume Fraction by Systematic Manual Point Count.” The candidate also will be useful to validate some commercial programs designed for the quantification of phases. The characterized alloy had a commercial origin and was purchased in the domestic market. For the intended purposes, the alloy must have high chemical and microstructural homogeneity. Therefore, the evaluation of homogeneity was done by optical microscopy, scanning electron microscopy, x-ray fluorescence, and x-ray diffraction and by the method in ASTM E562-11, to finally determine the phase content. Analysis of variance (ANOVA) provides a statistical test of whether or not the means of several groups are equal, and therefore generalizes the t test to more than two groups. ANOVAs are useful for comparing (testing) three or more means (groups or variables) for statistical significance. ANOVA was applied to evaluate the homogeneity of the alloy. This statistical tool is recommended in the ISO Guide 35:2006 to evaluate the variability among and within units. Precision was estimated under repeatability conditions. Precision obtained was of 5% and, according to the results of the ANOVA, it was found that the material is homogenous.