Microstructure characterization and hydrogen desorption behaviors of Mg-Al-H powders prepared by reactive milling in hydrogen
(1. Shanghai Engineering Research Center of Magnesium Materials and Applications,
School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China;
2. State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering,
Shanghai Jiao Tong University, Shanghai 200240, China)
School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China;
2. State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering,
Shanghai Jiao Tong University, Shanghai 200240, China)
Abstract: Microstructure and phase evolutions of Mg-Al powders ball milled in hydrogen atmosphere were investigated. Both in Mg-3%Al (mass fraction) and Mg-9%Al systems, β-MgH2 phase was observed upon a short milling time of 4 h and its maximum content of ~80% was reached after 32 h. Neither as-milled powders of the in the two systems contain Mg17Al12. However, heating the milled powders of Mg-9%Al powders to 350 °C resulted in the precipitation of Mg17Al12. DTA/TG analyses of those powders milled for 8-40 h showed that either well-developed peak doublets or shoulders were observed, which plausibly corresponded to the separate hydrogen desorption from different particle fractions of β-MgH2.
Key words: Mg alloy; reaction milling; hydriding; nanocrystalline magnesium hydride; peak doublets