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Metal Matrix Composites
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Design and Development of Next-generation Heat-resistant High Strength High Entropy Superalloy

Breif

The properties of the metallic materials used in extreme conditions such as next generation aerospace technologies and energy applications have significant effects on the performance of the entire system, while the improvement of the properties by changing small amount of alloy components has reached its limit. In order to overcome such limitations, development of new alloy design paradigm is high on demand. High entropy alloy system, which utilizes the increase in entropy of the system by mixing 5 or more elements with composition of 5~35 at%, has been considered as a promising approach. High entropy alloy systems are known to have high mechanical performance owing to high entropy of the system, lattice distortion, and slow diffusion rate resulting from mixing of different atomic species. While the most common processing technique used to fabricate the high entropy alloy has been cast method, it is limited to non-uniform microstructure and coarse grain size. The composite materials laboratory had fabricated high entropy alloys with improved mechanical properties by powder metallurgical process. By using high energy planetary ball milling, high entropy alloy powders were fabricated which was then sintered to make bulk alloy with enhanced mechanical properties. Moreover, in order to achieve additional improvement in mechanical properties, incorporation of oxide and carbide reinforcements in high entropy alloy matrix is being researched. In terms of the composition, fabrication and evaluation of an alloy system with elements with high thermal resistance, such as W, Nb, Mo, and another system with transition metal elements, such as Fe, Co, Cr are being done. The application of high entropy alloy is expected in gas turbine for space vehicles in the field of aerospace, thermally resistant alloys in the field of nuclear power, tool materials, mold and bearing materials.


Fig.1 Microstructure of high entropy alloy powder and bulk


Fig. 2 Application fields of high entropy alloys



Last CGI Updated: January 26, 2011
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