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      Advanced Design and Casting Process Development of MoSiB-Based Ultra-High Temperature Materials


      Science Impact, Ltd.

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          Professor Kyosuke Yoshimi, from the Department of Metallurgy, Materials Science and Materials Processing at Tohoku University in Japan, heads a team who are investigating a means of inventing a novel ultra-high-temperature material. One of the key focal points of his research targets improving the operating temperature limitations of nickel-based superalloys. The applications of such an endeavour are considerable and would particularly benefit energy conversion systems such as jet engines and gas turbines where the aforementioned nickel-based superalloys are used for high-pressure turbine blades. The project Yoshimi is currently engaged in began in 2008 and he had three things to consider before embarking on his research. First, his team needed to use a metallic phase for fracture toughness; secondly, they needed to develop a higher melting point for the metallic phase to ensure high temperature strength; and third, they had to consider using a lower density for the metallic phase in order to reduce weight, an important consideration in many engineering applications. Once these three considerations had been factored in, only a few elements in the periodic table proved suitable for closer examination. The team were left with two choices: using a niobium-based (Nb) system or a molybdenum-based (Mo) system. At that time, General Electric in the US had intensively studied Nb and Nb silicide-based multicomponent alloys for ultra-high-temperature applications beyond Ni-based (nickel) superalloys and therefore, many materials scientists and engineers were focused on the development of Nb and Nb silicide-based alloys. It was for those reasons that Yoshimi decided to concentrate on Mo. ‘Mo looked more attractive to me because of its insolubility in oxygen as well as its elastic moduli, that are much higher than those of Nb,’ explains Yoshimi. ‘These two properties are very important for high-temperature strength and oxidation resistance. Therefore, I decided to keep going with the Mo and Mo silicide-based alloys, the so-called Mo-Si-B-based (molybdenum-silicon-boron) alloys.’ Although there is still some way to go with their experiments, the team has demonstrated the potential for their invention of the first-generation MoSiBTiC alloy. The next phase will be to develop their invention for second-generation materials. The main hurdle has been overcome and it is now a case of refining their findings. ‘There is no doubt that ultra-high-temperature materials create ultra-high-temperature technology,’ explains Yoshimi. ‘Higher-temperature materials forming and machining, higher-temperature and pressure sintering, energy conversion, chemical reactions and other techniques will be achieved, and the new achievements will dramatically innovate existing technologies.’

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          Author and article information

          Science Impact, Ltd.
          December 12 2018
          December 12 2018
          : 2018
          : 9
          : 53-55
          © 2018

          This work is licensed under a Creative Commons Attribution 4.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/

          Earth & Environmental sciences, Medicine, Computer science, Agriculture, Engineering


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