Transformaciones de fase en aleaciones Zn-22%Al-2%Cu y Zn-22%Al-2%Cu-X (X = 1, 2 y 3%Ag) envejecidas isotérmicamente

Abstract

Phase transformations in Zn-22%Al-2%Cu and Zn-22%Al-2%Cu-X (X = 1, 2 and 3%Ag) alloys during aging treatments . The study of phase transformations that take place in Zn-22%Al-2%Cu and Zn-22%Al-2%Cu-X (X = 1, 2 and 3%Ag) alloys was carried out using X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Alloys were homogenized at 350 ° C during 10 days and quenched at ∼2 ° C. Subsequently, samples were aged at 200 ° C for different times. The initial microstructure consists in a matrix of fine equiaxial grains of α and η phases for all the alloys. Besides isolated particles of ε and Pdbl; were observed without and with Ag addition, respectively. During the aging, the four phase reaction, α + ε → η + τ', takes place to obtain the equilibrium η, α and τ' phases. However, the Ag addition promotes the formation of the Pdbl; phase, which retards or inhibits the four phase reaction. The stability of the Pdbl; phase is obtained with 3%Ag, which could improve the dimensional stability of the alloy for future industrial applications.