To overcome these disadvantages selected powder compacts were hipin addition. The microstructure of a hipped sample is shown in Fig. 7. It can be seen that the grainboundaries neither contain other phases nor pores although the sample is not fully dense yet. The electrical resistivity is now in the favorable range of about 10 cm and is maintained in this range even after reoxidation at 1000 ◦C for 2 h in air.