Powder metallurgy materials are special and have great potential in the aerospace field!

The weight of a commercial aircraft engine today typically ranges from 2,000kg to 8,500kg, with powder metallurgy materials accounting for 85% to 95% of the engine weight. Due to their unique combination of properties, including high strength and toughness, metals have been dominant due to their high resistance to degradation and good surface stability during hot engine cycles and in the severe oxidising and corrosive environments encountered during engine operation.

Powder metallurgy materials are special and play a huge role in aircraft engines!

The thermodynamic cycle determines the temperature and pressure of the gases, so it is important to find the right material for every part of the engine - from the front-end fan all the way through to the compressor, combustor and turbine.

For the fan, preference is given to low-density materials with high toughness for the paddles, with titanium alloys and polymer matrix composites, as well as some aluminium composites, being favoured for their productivity. The temperature of the air stream rises to 700°C as it passes through the compressor, which consists of titanium alloy blades and discs.

In the burner section, high-temperature nickel- and cobalt-based alloys (which are moderately strong and easy to machine) have become the main materials for the structure. After combustion, the gas temperatures are in the range of 1,400°C to 1,500°C. As they enter the high-pressure turbine, the rotating turbine blades are subjected to the combination of stresses and temperatures that are so intense in an engine.

Powder metallurgy

Turbine blades are unique aerothermal components with thin-walled, multi-layered structures that drive a complex internal cooling system. Currently, turbine blades are mainly made by applying an oxidation-resistant intermetallic bonding coating on a single-crystal nickel-based ultra-high-temperature-resistant alloy substrate followed by a porous, low-conductivity yttrium oxide-stabilised zirconium oxide topcoat as a thermal barrier.

The blades are attached to a turbine disc, which consists of a polycrystalline form of a nickel-based alloy. The disc, one of the Z-safety and critical components of the engine, is often formed by powder metallurgy and superplastic forging to Z-maximise strength and fatigue resistance.

With hot gas extraction from the turbine, the gas temperature is again reduced to a moderate level of less than 800°C. The rotating and stationary parts in the rear section of the turbine are dominated by polycrystalline cast nickel-based high-temperature alloys. As for the engine shaft, it must have high strength and fatigue resistance and is usually made of high-strength steel or nickel-based high-temperature alloys.