Over 300 Chinese J-20 stealth fighters have been built at roughly $110 million each. Not one carries a turbine blade that matches the service life of its Western equivalent. The WS-15 reached serial production on the J-20A in December 2025. Its high-pressure turbine runs on a third-generation Chinese single-crystal superalloy, rated about 30 degrees Celsius hotter than the second generation. The chemistry works. Casting yield at production scale does not. Chinese foundries scrap two of every three blades they cast. Western foundries scrap one in twenty. Chinese military engines improved from a few hundred hours between overhauls to roughly 1,500 with better blades. Western equivalents run roughly twice as long between overhauls and several times longer in total service life. Western foundries target sulfur below 1 part per million. Best practice runs below 0.3. At that purity, the coating survives thousands of hours in gas streams hotter than the alloy's melting point. A few extra parts per million and the coating peels, the blade oxidizes, and the engine fails prematurely.