Analysis of deformation twins and the partially dehydrogenated microstructure in nanocrystalline magnesium hydride (MgH2) powder

作者：Danaie M^*; Tao S X; Kalisvaart P; Mitlin D

来源：Acta Materialia, 2010, 58(8): 3162-3172.

DOI：10.1016/j.actamat.2010.01.055

• Hydrogen storage
• TEM
• Magnesium hydride

Cryo-stage transmission electron microscopy (TEM), supported by Density Functional Theory (DFT), is employed to explore the microstructure of magnesium hydride (MgH2) powders. Mechanical milling results in deformation twinning of the hydride The crystallography of the twins is established DFT analysis shows that the twin unit cell is just as thermodynamically stable as the undeformed alpha-MgH2 matrix It is hypothesized that the twins contribute significantly to the observed milling-induced kinetic enhancement by acting as high diffusivity paths for hydrogen Energy-filtered TEM analysis on partially desorbed MgH2 demonstrates that nucleation and growth of metallic magnesium occurs non-uniformly Larger powder particles are a composite of isolated magnesium grains heterogeneously nucleated on the remaining hydride Smaller particles are either fully transformed to magnesium or remain entirely a hydride There is little evidence for any "core shell" structure It is also shown that in situ hy

• 出版日期2010-5