[en] The precipitation hardened Inconel X-750 is extensively used in both PWR and BWR as bolts, pins, spring components, etc., mainly because of this alloy's excellent high temperature strength and good oxidation and corrosion resistance. However, this alloy has experienced some intergranular stress corrosion cracking. It has been reported that the SCC resistance of Inconel X-750 can be improved by direct aging in the precipitation regime of 704 to 871⁰C. Therefore, the microstructural changes that occur when Inconel X-750 is thermally treated between 704⁰C and 871⁰C for up to 200 hours following a 2-hour solution anneal at 1075⁰C, or 1149⁰C, or 1204⁰C has been studied. Optical, transmission electron, and scanning and Auger electron microscopy were used in order to establish the most appropriate aging sequence for this alloy which will produce a suitable precipitation morphology and distribution of secondary carbides and intermetallics. The precipitation morphology and analysis of γ' (L1₂), secondary M₂₃C₆ and primary MC carbide phases for each heat treatment cycle were studied using TEM techniques. The coarsening kinetics of the γ' particle growth obeyed the time-law prediction of Lipshitz-Slazor-Wagner theory of diffusion controlled growth at all aging temperatures. The γ' precipitate lost coherency by the nucleation of dislocation loops within the precipitate, the interaction of dislocation at the interface and attraction of matrix dislocations to the particle/matrix interface