Fabrication and Properties of Porous TiAl Based Intermetallics

초록

The porous Ti-45at.%Al-1.6at.%Mn intermetallics were fabricated by reactive sintering process using the extruded mixtures consisting of elemental titanium and aluminum alloy powders. And the microstructure and mechanical properties were investigated. At the extrusion stage, three different extrusion ratios were tried in order to provide the various types of porous structure in the microstructure. It was clearly found that the shape of pore is largely dependent on extrusion ratio. With increasing extrusion ratio the aspect ratio of porous structure increased. It was also revealed that the porosity of the specimen could be controlled by the heating rate at the reactive sintering stage. The porosity decreased with increasing heating rate. The subsequent heat treatment was done for the reactively sintered specimens in order to control the microstructure of the matrix. The results of compressive test showed that the strength of heat-treated specimens changes with porosity and the shape of pore. An exceptionally high ultimate strength about 960MPa was obtained at room temperature in the specimen with the porosity of 33% and the aspect ratio of 11, having a fully lamellar structure in the matrix.