Materials and Structural Problems

Whittle’s W-1 engine developed around 1940 had austenitic steel turbine blades, but by September 1942, he had already turned to high-nickel alloys. Whittle’s engine had a turbine inlet temperature of 718°C, but today’s engine run at about 1,500°C. As the years passed and the temperature climbed, engines had to adopt superalloys mostly of nickel and cobalt. The first superalloys had about 20% Cr, enough to protect against high-temperature oxidation (corrosion), and later the chromium was cut back by adding aluminum (“aluminium” in British literature) and titanium. Single-crystal alloys (monocrystal alloy), where the entire blade is made of a single crystal, have appeared also, with very good effect.