The rhenium containing second generation single crystal alloy CMSX-4® was introduced for turbine blading in the Solar® Turbines Incorporated Mars® T-14000 engine in 1990. Based on the initial success with the first 4,000 hour engine test, the alloy was confirmed as bill of material for the stage 1 turbine blades in the T-14000 engine. Field experience has been excellent and there are now about 1,500,000 hours total accumulated engine time with several engines having completed their first overhaul cycle (Typically 30,000 hours). Use of this alloy is now being considered by Solar for other turbine airfoil components.

This update provides the results of metallurgical evaluations on high time blades. A detailed analysis of the substrate and coating, microstructure following the 25,000 hours field exposure was conducted and the results reported herein. A brief discussion of the effect of PtAl coatings on fatigue properties is also included.

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