Densification Behavior of Nanocrystalline Mg2Si Compact in Hot-pressing

Densification behavior of nanocrystalline Mg2Si (n-Mg2Si) with grain size about 30-50 nm was investigated by hot-pressing at 400℃. The results indicated that the densification process of n-Mg2Si exhibited three linear segments: p＜0.3 GPa, 0.3 GPa＜p＜1.2 GPa, and p＞l.2 GPa determined by Heckel formula, among which the third fast increasing segment in high pressure range p＞1.2 GPa has seldom been reported in conventional coarse-grained polycrystalline materials. Nevertheless, in the whole pressure range (0.125-1.500 GPa) investigated the densification behavior of n-Mg2Si can be well described by a Kawakita formula p/C=(1/a)p 1/(ab) with constant a=0.452 being in good agreement with the initial porosity of the compact.