Fabrication of unidirectional porous TiAl–Mn intermetallic compounds by reactive sintering using extruded powder mixtures

The unidirectional porous Ti–45at.%Al–1.6at.%Mn intermetallic compounds having fully lamellar structure were fabricated by reactive sintering method using the extruded mixtures consisting of elemental titanium and aluminum-manganese powders. The average porosity of the specimens is measured to have a distribution in the range from 25% to 35% in volume fraction within the experimental conditions investigated. The porosity of the specimen produced decreased with increasing heating rate in the reactive sintering process. The maximum porosity of 35% can be obtained when the specimen was reactively sintered under the heating rate of 0.17 K/s. The porosity of the reactively sintered specimen can be controlled by a variation of heating rate. From the microstructural observation, we found a directionality of pores oriented parallel to the extrusion direction and suggested that an aligned-structure of pores of the present alloy is closely associated with the extrusion microstructure consisting of elongated feature of constituent mixtures.