Hypergravity aids development of aircraft-grade alloy

The titanium aluminide alloy is claimed to be half the weight of conventional nickel superalloys and capable of withstanding temperatures of up to 800°C. While such alloys have long been of interest to aircraft engine manufactures, the difficulties faced in casting the material into shapes such as turbine blades has made it unsuitable for use. The ESA scientists decided to look into this problem to gain a greater understanding of the natural processes that take place during casting. They began by heating aluminium samples in a small furnace carried in a sounding rocket. During six minutes of free fall, the samples were heated to over 700°C and then monitored by X-rays as they cooled. The results revealed to the researchers that casting titanium aluminides might require looking in the opposite direction: hypergravity. The team turned to the agency's centrifuge in the ESTEC research and technology centre in the Netherlands to test their theory. They found that casting the metals in a centrifuge at up to 20 times normal gravity helped the liquid metals to fill every part of a mould, producing a perfectly cast alloy, even with complex shapes. The researchers believe the breakthrough could provide the building blocks for allowing the industrial process to be refined and commercialised – potentially enabling the weight of jet engine turbines to be reduced by as much as 45%.