Microstructure of Free MgO Powder

The aim of this research is to study the Microstructure behavior of pure MgO free (uncompacted) powders and MgO added to magnesium chloride(MgC/2 ) free powders with different doping rates (1%, 38% , 44%, and50%) . The sintering temperah1res were taken from7oo ·c to 1600C in Ioo ·c steps. The sintering times were taken 3 hr, 24 hr, and 48 hr.The essential contribution of this work consists of new results in microstructure development . First , increasing the concentration of magnesium chloride (~50%) led to obtain single ultrafine grains at low temperatures . secondly , the formation of a new structure that is the fiber structure at sintering conditions (temperature and time) ; llOO C ,48hr for magnesium oxide added to 44% magnesium chloride powders . while reducing the ratio of the additive material ; magnesium chloride to (~ 1%) led to decrease the sinteri ng temperature and sintering time to 1000 · C and 3hr , respectively which is required to the fiber formation . An important structure is recognized at the intermediate stage of sintering, this is the Kelvin s tetrakaidecahedron. This occurred at sintering temperahtre 1100 · C, 24 hr sintering time for 44% magnesium chloride added with magnesium oxide powders