Hot isostatic consolidation and transformation of sigma phase powders

Superferritic stainless steel compositions containing 38%Cr and at least 2% each of Ni and Mo carl be converted to sigma phase by heat treatment and t hen to powder by mechanical attrition. This powdered sigma phase has been e xperimentally processed by powder metallurgical techniques to produce green compacts which were consolidated in a hot isostatic press. Depending on co mposition, several of the powdered alloys were converted back to ferrite du ring hipping. The mechanism of the consolidation process, the nature of the microstructures produced, and the prognosis for its industrial exploitatio n are examined.