AbstractThe effect of solution treatment temperature on both the morphology of grain boundary carbides and the creep rupture behaviour of Inconel alloy X-750 has been investigated. Solution treatment at 1050°C led to precipitation of Ti/Nb carbide along grain boundaries, and as a result the formation of chromium carbide during subsequent aging treatment was considerably affected. This led to changes in the morphology of the grain boundary carbide and reduction in the width of‘clear’zone. This modification in the morphology of grain boundary carbide reduced the creep resistance of the alloy, leading to a reduction in rupture lifetimes, whereas strains tofracture were unaffected.MST/1981