Effect of heat treatment on the electrical conductivity of ZM51 magnesium alloy

Abstract

Abstract The microstructures and electrical conductivity of extruded Mg-5.38 wt.%Zn-0.88 wt.%Mn (ZM51) magnesium alloys under four different heat treatments (T5: single aging, two-stage aging; T6:T4+single aging, T4+two-stage aging) were investigated by optical microscopy (OM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and conductivity test. The results show that the electrical conductivity of alloys after different heat treatments was increased with the aging time increasing identically. The conductivity of T6 ZM51 alloy is lower than that of T5 treatment alloy, and the conductivity of alloy with two-stage aging is higher than that of alloys with single-stage aging. In the two-stage aging, the time of pre-aging at low temperature formed dense GP zones which can serve as the nucleation core of the β1’ phases, and the formed β1’ phases are more diffuse and fine, and the scattering of free electrons are lower. The electrical conductivity of the alloy increased first and then reduced with the increase of the pre-aging time, and the reason is that the alloys form a more diffuse GP zones after pre-aging for 32h, which can be used as the heterogeneous nucleation core of β1’ phases, so that the precipitation of the β1’ phases are more finely dispersed, thereby increasing the scattering capacity of free electrons.