Criterion for Sigma Phase Formation in Cr- and V-Containing High-Entropy Alloys

Formation of the σ phase has been observed in quite a few high-entropy alloys (HEAs) recently. The σ phase significantly enhances the hardness of the alloys but reduces their ductility. Thus, controlling the formation of σ phase through proper design is critical for HEAs. However, theories to predict the σ phase formation based on HEA composition are still not available. Here, we demonstrate that the σ phase formation is directly related to the valence electron concentration (VEC) of the alloy. The σ-phase-forming VEC range was systematically studied and revealed. Such finding is of crucial importance to the future design of HEAs.

[1]  L. Tsao,et al.  Age hardening reaction of the Al0.3CrFe1.5MnNi0.5 high entropy alloy , 2012 .

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

[3]  U. Mizutani,et al.  Electronic structure of Hume-Rothery phases , 1978 .

[4]  J. Yeh,et al.  On the superior hot hardness and softening resistance of AlCoCrxFeMo0.5Ni high-entropy alloys , 2011 .

[5]  Yuntian Zhu,et al.  Significant hardening due to the formation of a sigma phase matrix in a high entropy alloy , 2013 .

[6]  J. Yeh,et al.  Mechanical performance of the AlxCoCrCuFeNi high-entropy alloy system with multiprincipal elements , 2005 .

[7]  J. Gan,et al.  Thermal Stability and Performance of NbSiTaTiZr High-Entropy Alloy Barrier for Copper Metallization , 2011 .

[8]  Zhongyi Liu,et al.  Aging behavior of a CuCr2Fe2NiMn high-entropy alloy , 2012 .

[9]  J. Yeh,et al.  Microstructure and wear behavior of AlxCo1.5CrFeNi1.5Tiy high-entropy alloys , 2011 .

[10]  水谷 宇一郎,et al.  Hume-Rothery rules for structurally complex alloy phases , 2011 .

[11]  Masahiko Morinaga,et al.  New Phacomp and its Applications to Alloy Design , 1984 .

[12]  Nikita Stepanov,et al.  Tensile properties of an AlCrCuNiFeCo high-entropy alloy in as-cast and wrought conditions , 2012 .

[13]  C. S. Barrett.  Structure of Metals; Crystallographic Methods, Principles, and Data , 1966 .

[14]  Hsien-Lung Tsai,et al.  Effect of aging treatment on microstructure and properties of high-entropy Cu0.5CoCrFeNi alloy , 2010 .

[15]  Zushu Hu,et al.  Synthesis and properties of multiprincipal component AlCoCrFeNiSix alloys , 2010 .

[16]  J. Yeh,et al.  Microstructure and properties of age-hardenable AlxCrFe1.5MnNi0.5 alloys , 2010 .

[17]  C. Li,et al.  Effect of alloying elements on microstructure and properties of multiprincipal elements high-entropy alloys , 2009 .

[18]  C. Liu,et al.  Phase stability in high entropy alloys: Formation of solid-solution phase or amorphous phase , 2011 .

[19]  Jien-Wei Yeh,et al.  Effect of vanadium addition on the microstructure, hardness, and wear resistance of Al0.5CoCrCuFeNi high-entropy alloy , 2006 .

[20]  Sheng Guo,et al.  Entropy-driven phase stability and slow diffusion kinetics in an Al0.5CoCrCuFeNi high entropy alloy , 2012 .

[21]  Yuan-Sheng Huang,et al.  On the elemental effect of AlCoCrCuFeNi high-entropy alloy system , 2007 .

[22]  Fujiwara.  Electronic structure in the Al-Mn alloy crystalline analog of quasicrystals. , 1989, Physical review. B, Condensed matter.

[23]  J. Yeh,et al.  Microstructure characterization of AlxCoCrCuFeNi high-entropy alloy system with multiprincipal elements , 2005 .

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

[25]  J. Joubert.  Crystal chemistry and Calphad modeling of the σ phase , 2008 .

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