ESA researchers use hypergravity to cast exotic alloy

Engineers at the European Space Agency (ESA) have developed an innovative casting process that could help an exotic new lightweight alloy fulfil its promise in the aerospace industry.

Twice as light as conventional nickel superalloys and able to withstand temperatures of up to 800°C titanium aluminide alloys have long been regarded as extremely attractive.
However, although it’s possible to make the alloy in a laboratory, casting it in the shapes required by industry, such as a turbine blade, is not simple.

Working as part of ESA’s IMPRESS (Intermetallic Materials Processing in Relation to Earth and Space Solidification) the team began its investigations by testing the behaviour of a heated titanium aluminide alloy in microgravity.

A small furnace was launched with a sounding rocket from Kiruna, Sweden, and the cooling process was monitored with X-rays, but the result convinced them to pursue the opposite effect: hypergravity.

The team headed to ESA’s research and Technology Centre (ESTEC) at Noordwijk in the Netherlands where heated samples of the material were placed in moulds attached to the facility’s large diameter centrifuge. By subjecting the metal to 20 times normal gravity, the group discovered that the liquid metal filled every part of the mould and created a perfectly cast alloy, even with relatively complex shapes.