Solidification Microstructures of the Ingots Obtained by Arc Melting and Cold Crucible Levitation Melting in TiNbTaZr Medium-Entropy Alloy and TiNbTaZrX (X = V, Mo, W) High-Entropy Alloys

The solidification microstructures of the TiNbTaZr medium-entropy alloy and TiNbTaZrX (X = V, Mo, and W) high-entropy alloys (HEAs), including the TiNbTaZrMo bio-HEA, were investigated. Equiaxed dendrite structures were observed in the ingots that were prepared by arc melting, regardless of the position of the ingots and the alloy system. In addition, no significant difference in the solidification microstructure was observed in TiZrNbTaMo bio-HEAs between the arc-melted (AM) ingots and cold crucible levitation melted (CCLM) ingots. A cold shut was observed in the AM ingots, but not in the CCLM ingots. The interdendrite regions tended to be enriched in Ti and Zr in the TiNbTaZr MEA and TiNbTaZrX (X = V, Mo, and W) HEAs. The distribution coefficients during solidification, which were estimated by thermodynamic calculations, could explain the distribution of the constituent elements in the dendrite and interdendrite regions. The thermodynamic calculations indicated that an increase in the concentration of the low melting-temperature V (2183 K) leads to a monotonic decrease in the liquidus temperature (TL), and that increases in the concentration of high melting-temperature Mo (2896 K) and W (3695 K) lead to a monotonic increase in TL in TiNbTaZrXx (X = V, Mo, and W) (x =  0 − 2) HEAs.

[1]  T. Nakano,et al.  Solidification Microstructure of High Entropy Alloys Composed With 4 Group (Ti, Zr, Hf), 5 Group (V, Nb, Ta), and 6 Group (Cr, Mo, W) Elements , 2019, Materia Japan.

[2]  J. Zou,et al.  A novel quaternary equiatomic Ti-Zr-Nb-Ta medium entropy alloy (MEA) , 2018, Intermetallics.

[3]  T. Nakano,et al.  Microstructure of equiatomic and non-equiatomic Ti-Nb-Ta-Zr-Mo high-entropy alloys for metallic biomaterials , 2018, Journal of Alloys and Compounds.

[4]  Daniel B. Miracle,et al.  Development and exploration of refractory high entropy alloys—A review , 2018, Journal of Materials Research.

[5]  T. Nagase,et al.  Microstructure of Ti-Ag immiscible alloys with liquid phase separation , 2018 .

[6]  Peter K. Liaw,et al.  Science and technology in high-entropy alloys , 2018, Science China Materials.

[7]  Jian Xu,et al.  TiZrNbTaMo high-entropy alloy designed for orthopedic implants: As-cast microstructure and mechanical properties. , 2017, Materials science & engineering. C, Materials for biological applications.

[8]  J. Qiao,et al.  Mechanical properties of refractory high-entropy alloys: Experiments and modeling , 2017 .

[9]  Aira Matsugaki,et al.  Novel TiNbTaZrMo high-entropy alloys for metallic biomaterials , 2017 .

[10]  Hongwei Yao,et al.  MoNbTaV Medium-Entropy Alloy , 2016, Entropy.

[11]  M. Gao,et al.  Design of Refractory High-Entropy Alloys , 2015 .

[12]  Yong Zhang,et al.  Prediction of high-entropy stabilized solid-solution in multi-component alloys , 2012 .

[13]  C. Woodward,et al.  Microstructure and elevated temperature properties of a refractory TaNbHfZrTi alloy , 2012, Journal of Materials Science.

[14]  C. Woodward,et al.  Microstructure and Room Temperature Properties of a High-Entropy TaNbHfZrTi Alloy (Postprint) , 2011 .

[15]  C. Liu,et al.  Effect of valence electron concentration on stability of fcc or bcc phase in high entropy alloys , 2011 .

[16]  D. Miracle,et al.  Mechanical properties of Nb25Mo25Ta25W25 and V20Nb20Mo20Ta20W20 refractory high entropy alloys , 2011 .

[17]  P. Liaw,et al.  Refractory high-entropy alloys , 2010 .

[18]  P. Liaw,et al.  Solid‐Solution Phase Formation Rules for Multi‐component Alloys , 2008 .

[19]  B. Cantor,et al.  Microstructural development in equiatomic multicomponent alloys , 2004 .

[20]  T. Shun,et al.  Nanostructured High‐Entropy Alloys with Multiple Principal Elements: Novel Alloy Design Concepts and Outcomes , 2004 .

[21]  S. Ranganathan,et al.  Alloyed pleasures: Multimetallic cocktails , 2003 .

[22]  T. Shibayanagi,et al.  Fabrication and Applications of Rapidly Quenched Metals , 1998 .

[23]  T. Maruyama,et al.  Solidification Microstructure of AlCoCrFeNi2.1 Eutectic High Entropy Alloy Ingots , 2017 .

[24]  M. Gao,et al.  High-Entropy Alloys: Fundamentals and Applications , 2016 .

[25]  L. Vegard,et al.  Die Konstitution der Mischkristalle und die Raumfüllung der Atome , 1921 .