Abstract
Close microstructural examination has been made on Ti-(40- 47.3)mol%Al-(1.4- 1.7)mol% Mn intermetallics produced by a reactive sintering using both Na-reduced Ti powders (Na-Ti powders), and Mg-reduced and subsequently hydride-dehydride Ti powders (HDH-Ti powders). The microstructure of compacted mixtures has also been measured.
When HDH-Ti powders are used as a starting Ti powder, both compacted and sintered microstructures have a fine and uniform distribution for all compositions. In contrast, if Na-Ti powders are used as a starting Ti powder, the compacted structure contains a segregated block area of Ti or Al alloys, depending on composition, which results in a coarse α2 structure or a group of y grains in sintered condition. Such inhomogeneous and non-uniform structures are considered to reduce the ductility of sintered materials.
Sintered materials using HDH-Ti powders have a larger grain size and limited micro pore, compared to the materials using Na-Ti powders, due to the reduced chlorine content.
