Origin of porosity in oxide-dispersion-strengthened alloys produced by mechanical alloying

Oxide-dispersion-strengthened (ODS) alloys produced by mechanical alloying (MA) are very prone to the occurrence of porosity. The reason for this has not been fully understood so far. In this work, a model ferritic ODS alloy has been examined by optical microscopy and scanning electron microscopy in both the powder form and the consolidated condition. Submicron-sized pores have been found in the as-mechanically alloyed powder and in the consolidated alloy. Moreover, pores can be observed in loose powder particles annealed at 1000 degreesC and 1100 degreesC. Based on these results, it has been suggested that the MA process might be largely responsible for the porosity problem in ODS alloys.