Jun 30, 2017 | By Benedict

Researchers at Singapore's A*STAR Institute of Manufacturing Technology and Institute of Materials Research and Engineering have improved the physical, thermal, and mechanical properties of 3D printable superalloys using titanium diboride nanoparticles.

Superalloys, alloys that are capable of withstanding high temperatures and stresses, have proven themselves incredibly useful to scientists. Materials like Hastelloy, Inconel, and Waspaloy are frequently used to build turbine engines due to their supreme resistance to heat, and future applications could be many and varied.

Scientists at A*STAR, Singapore’s Agency for Science, Technology and Research, recently carried out research that could make superalloys even better. By adding special nanoparticles to 3D printed superalloys, the researchers (from both the Singapore Institute of Manufacturing Technology and Institute of Materials Research and Engineering) have managed to make the materials stronger, reducing the chance of breakage.

Inconel 625, a superalloy that the A*STAR researchers have been focusing on, is 55-70 per cent nickel with added chromium, molybdenum, iron, niobium-tantalum, plus trace amounts of numerous other metals. The superalloy is frequently used in industrial marine applications because of its high corrosion-fatigue strength, tensile strength, and resistance to chloride-ion stress-corrosion cracking.

But by adding titanium diboride nanoparticles, the Singapore researchers think they have made Inconel 625 even stronger. The technique of laser-aided additive manufacturing (LAAM) was used to add these nanoparticles, with the scientists grinding and mixing an Inconel 625 alloy powder with a titanium diboride powder with particles roughly 58 nanometers in size.

The 3D printer used for the process consisted of a powder nozzle on a six-axis robot, as well as a high-power fiber laser. Using the advanced metal 3D printer, the scientists were able to create one-millimeter thick layers of the reinforced superalloy on a carbon steel substrate, which they built up into a rectangular block of 120 × 70 × 10 millimeters.

“We show that adding nanoparticles to the metal base material is an effective way to tailor the material with significantly improved physical, thermal, and mechanical properties, as well as excellent performance in terms of wear and corrosion resistance,” said Guijun Bi, one of the researchers working on the project.

After they had 3D printed the material, the researchers analyzed the superalloy and found that the titanium diboride nanoparticles mainly aggregated at boundaries between crystalline grains of the Inconel 625. The titanium diboride therefore acted to reinforce the grain boundary.

Once they had put the superalloy under the microscope, the researchers then put it through a more punishing evaluation, mechanically testing the sample to see if there were signs of increased material strength, high micro-hardness, and good abrasive resistance. All the boxes were ticked, leading the researchers to believe their work shows promise for the next generation of superalloys.

“We hope to develop this approach and explore new composite materials reinforced with nanoparticles for additive manufacturing,” Bi said.

A*STAR launched a $15 million 3D printing initiative back in 2013. The initiative included the development of the laser-aided additive manufacturing 3D printing technology used in the superalloy study.

 

 

Posted in 3D Printing Materials

 

 

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