CMSX-4(SLS)[La+Y] alloy is an improved version of CMSX-4 which is pre-alloyed with La and Y and has consistent low sulfur content of 1 ppm. Casting trials with pre-alloyed CMSX-4(SLS)[La+Y] ingot have demonstrated improved control and retention of La+Y content compared to traditional Ni-foilwrapped add packets attached to the charge increment at the casting furnace. The effectiveness of add packets is dependent upon melt-in and subsequent induction stirring prior to pour. Pre-alloying the ingot provides greater consistency of the reactive additions within the molten alloy and reduces the hold time at temperature needed to tie up the residual sulfur, minimizing reactive element loss during remelt. In addition, due to the consistent, low sulfur content of CMSX-4(SLS)[La+Y], smaller La+Y retentions are needed to obtain the same superior bare oxidation properties and coating/TBC life [32].

CMSX-4 alloy is ideal for small solid uncooled parts in the hottest applications of missile & small turbine engines. CMSX-4(SLS)[La+Y] offers improved oxidation resistance for bare alloy and/or coated conditions.

SUMMARY

Ni-base cast superalloys offer an outstanding combination of properties and performance which are desirable for small microturbine, turbojet, turbocharger and missile engine components. Representative properties and applications for equiaxed, directionally solidified and single crystal cast components have been discussed. The potential benefits include improved temperature capability and durability, along with economical manufacture of complex configurations for these engine programs.