In-situ HEXRD study on the β→α transformation in Al alloy EN AW-6063

Abstract

The present study employs in-situ high-energy X-ray diffraction (HEXRD) to investigate the β-AlFeSi→α-Al(Fe,Mn)Si transformation in a 6063 Al alloy during homogenization heat treatment. The characteristics of HEXRD, combined with the experimental setup, enable an evaluation of the evolution of individual diffraction peaks as a function of temperature and time. The diffraction intensity evolution is then used to quantify the transformation into phase fractions using the reference intensity ratio (RIR) method. The β-AlFeSi→α-Al(Fe,Mn)Si transformation is measured at the homogenization temperatures: 540, 550, 560, 570, 580, 590, and 600 °C. In addition, three heating rates (4, 50, 100 °C/min) are studied to observe the influence of the heating stage on the transformation onset. The growth of α at the expense of β dissolution is faster at higher temperatures, and is limited by the diffusion of Mn. At the same time, during the heating ramp, the evolution of α and β fractions indicates a two-stage transformation, characterized by different growth rates of α.