Heat-resistant alloy of 1,700 degrees Celsius for hypersonic vehicles

A three-year experiment on China’s Tiangong space station has yielded groundbreaking results that could improve the performance of rockets and hypersonic vehicles. Specifically, scientists used this data to create new materials: niobium-silicon alloy, Interesting Engineering reported on January 7. New research published in the journal Acta Physica Sinica.

With its ability to withstand extremely high temperatures, niobium-silicon is ideal for high-performance aircraft engines. The blades of turbofan engines made from this alloy can withstand temperatures above 1,700 degrees Celsius.

Niobium is a rare metal, mainly used in high-strength steel. Niobium-silicon alloys are also extremely difficult to produce. To date, this alloy has faced two major challenges in mass production: slow crystal growth and brittleness.

The process of forming durable crystals usually takes a long time – about 100 hours at a temperature of nearly 1,600 degrees Celsius. Furthermore, the resulting material is very brittle at room temperature, not suitable for use in engines.

The research team of professor Wei Bingbo at Northwestern Polytechnic University, an academician of the Chinese Academy of Sciences (CAS), overcame these challenges. They developed a rapid cooling method that allows the production of high-quality niobium-silicon crystals at a speed of nearly 9 cm per second, significantly reducing production time compared to traditional methods.

The team also added a small amount of hafnium to the alloy, thereby increasing its strength at room temperature by more than three times. This innovation solves the problem of brittleness, making the alloy suitable for engine manufacturing.

The microgravity environment on the space station changes the behavior of materials relative to Earth. In this environment, processes such as crystal growth and solidification occur very differently. When conducting microgravity experiments, scientists observed a number of unique phenomena.

For example, during the rapid hardening of the niobium-silicon alloy, a special shrinkable porous structure forms in a microgravity environment – unlike what is commonly found on Earth. These studies led to the development of a new niobium-silicon alloy that scientists call “a gift from heaven.”