Pore structures and thermal insulating properties of high Nb containing TiAl porous alloys

High Nb containing TiAl alloys have been investigated traditionally as potential high temperature structural materials. Another interesting field where high Nb containing TiAl porous alloys were firstly fabricated by elemental powder metallurgy (EPM) is shown in this study. The effects of fabrication processes on pore structures and thermal insulating properties of Ti–48Al–6Nb porous alloys were investigated. It was found that pores were generated along the resultant skeletons consisting of typical γ-TiAl/α2-Ti3Al fully lamellar (FL) microstructure for Ti–48Al–6Nb porous alloys. With the increasing of cold pressures and the fining of particle sizes of Ti and Al elemental powders, the sizes of skeletons and pores for Ti–48Al–6Nb porous alloys decrease. The pore sizes of Ti–48Al–6Nb porous alloys are normal distributions. With the increasing of cold pressures, the pore size distribution curves are in the direction of the smaller pore size and the distribution widths do not basically change. However, the pore size distribution curves become narrower and the peaks of curves move to the left with the fining of particle sizes. Thermal conductivity of Ti–48Al–6Nb porous alloys is a linear function of total porosity and the average pore size at room temperature, respectively. The thermal conductivity linearly increases when the service temperature increases from room temperature to 800 °C.