Segregation and precipitation formation for in situ oxidised 9Cr steel powder

Powder and sintered bulk materials of a reduced activation steel with oversaturated Ti and Y are prepared by gas atomisation and sintering. Segregation on both the surface and interior of the powder particles are observed after an thermal treatment. The oxidation of the segregates promotes formation of clusters of large Y oxide crystals and thick continuously distributed Ti oxide layers on the surface of the powder particles. The oxidation also occurs within the powder particles and mainly forms larger Ti oxide dispersoids in the grain boundaries of the powder. The coarsening and aggregation of the oxide dispersoids occur with increasing duration of the thermal treatment. Yttrium is also segregated and precipitated in the grains of the powder particles.