Understanding and designing good glass formers in Zr-Al-Co-(Nb) system combining clusters and mixing entropy

Abstract

Abstract Bulk alloy compositions in Zr-Al-Co-(Nb) system were understood and designed using our clusters- and mixing entropy-related method. Glass formers in Zr-Al-Co system were regarded as a mixture of Zr-Al and Zr-Co binary clusters with specific ratio. Icosahedral atomic clusters Co-Co 3 Zr 9 , Co-Co 6 Zr 6 , Al-Al 4 Zr 8 and an Archimedean octahedral anti-prism cluster Al-Al 2 Zr 8 were obtained and used. The coefficients of clusters were designed by mixing entropy. Only four compositions were designed. Among those, alloy with highest GFA was achieved at the composition of Zr 53.6 Al 18.6 Co 27.8 which enjoyed the same glass forming ability (GFA) as the well-known Zr 56 Al 16 Co 28 under the same condition. A series of compositions minor alloyed by Nb were further designed and analyzed. The results show that the optimum addition content of Nb could further enhance the GFA. Through the perspective of clusters and mixing entropy, it was assayed qualitatively the origin of enhancing GFA by minor-alloying element, which might help build a foundation for quantitative analysis of minor alloying.