S0401-1-4 Solid State Reaction of Magnesium Alloy with Calcium Oxide by Bulk Mechanical Alloying

Powder metallurgy magnesium composites reinforced with calcium oxides (CaO) were fabricated by using equal channel angular bulk mechanical alloying process (ECABMA), when using AZ61 B as the matrix material. In-situ formed compounds were investigated by XRD, DTA and SEM/EDS analysis. In the case of AZ61 B added with CaO particles, the fabrication of Al_2Ca and MgO occurred by reducing CaO during annealing the composite. The higher content of CaO caused the lower forming temperature of Al_2Ca. For example, Al_2Ca phase was synthesized by annealing at more than about 550℃ and 420℃ in 2.5 and 10 vol.% CaO added AZ61 B, respectively. On the other hand, in over 5 vol.% CaO added AZ61 B, Al_2Ca compound was decomposed and (Mg,Al)_2Ca phase was formed by annealing at more than about 550℃. This reaction never occurred in the case of AZ61 B alloys including 2.5 vol.% CaO.