Study on precipitation kinetics of discontinuous cellular Mg 17 Al 12 phase and corrosion behavior of Mg-13Al alloy

Abstract

Due to the low standard electrode potential of Mg-13Al alloy, it is prone to corrosion, greatly limiting its application. In this work, the corrosion resistances and microstructures of Mg-13Al alloy with different aging treatments were investigated. Meanwhile, the relationship between the volume fraction of discontinuous cellular Mg₁₇Al₁₂ phase (y) and corrosion rate (Ia) is established, which is described as Ia = 5.36 + 0.37y¹-0.01y² + 1.25 × 10⁻⁴y³. Moreover, to further confirm the effect of different aging treatment conditions on the Ia, the precipitation kinetics equations of discontinuous cellular Mg₁₇Al₁₂ phases at 125°C, 135°C and 145°C are obtained, as follows: y = 1-exp(−3.232 × 10⁻⁵t^3.3), y = 1-exp(−3.078 × 10⁻⁴t^2.7) and y = 1-exp(−1.081 × 10⁻³t^2.9). Combined three kinetics equations above with Ia corresponding to y, the Ia corresponding to different aging processes can be quantitatively estimated.