Pile-up and sink-in nanoindentation behaviors in AlCoCrFeNi multi-phase high entropy alloy

Abstract Microstructures and nanoindentation behaviors were studied on annealed AlCoCrFeNi high entropy alloy. Both pile-up and sink-in characteristics were found in the grain boundary and grain regions, respectively. The multiple phases present in the AlCoCrFeNi high entropy alloy are the reasons behind the different nanoindentation behaviors, which were identified using electron microscopy. The identified phases showed the grain boundary segregation to have A1 lattice, viz., FCC structure while the grain was distributed with A2 and B2 lattices, viz., BCC and ordered BCC structures, forming the matrix with nano-precipitates of the other. The reason for the pile-up and sink-in is attributed to the dislocation activity in the individual crystal structure: large dislocation activities were found under the pile-up and little dislocation activities under the sink-in, only limited to the indenter tip. Results from a finite element analysis under an isotropic elasto-plastic condition by varying the hardness-to-modulus ratio show that high hardness-to-modulus ratio results in pile-up and the lower ratio results in sink-in. This was associated with the susceptibility to plasticity and the elastic recovery for individual phases of the AlCoCrFeNi high entropy alloy.

[1]  J. Yeh,et al.  The effect of molybdenum on the corrosion behaviour of the high-entropy alloys Co1.5CrFeNi1.5Ti0.5Mox in aqueous environments , 2010 .

[2]  Alexei Bolshakov,et al.  Influences of pileup on the measurement of mechanical properties by load and depth sensing indentation techniques , 1998 .

[3]  K. Dahmen,et al.  Microstructures and properties of high-entropy alloys , 2014 .

[4]  J. Dusza,et al.  Orientation-dependent hardness and nanoindentation-induced deformation mechanisms of WC crystals , 2015 .

[5]  J. Yeh,et al.  Sluggish diffusion in Co-Cr-Fe-Mn-Ni high-entropy alloys , 2013 .

[6]  Zhihua Wang,et al.  Plastic Deformation of Al0.3CoCrFeNi and AlCoCrFeNi High-Entropy Alloys Under Nanoindentation , 2015, Journal of Materials Engineering and Performance.

[7]  G. Pharr,et al.  Measurement of hardness and elastic modulus by instrumented indentation: Advances in understanding and refinements to methodology , 2004 .

[8]  Jien-Wei Yeh,et al.  High-Entropy Alloys , 2014 .

[9]  Y. Lai,et al.  Strain Rate Dependence on Nanoindentation Responses of Interfacial Intermetallic Compounds in Electronic Solder Joints with Cu and Ag Substrates , 2009 .

[10]  A. Elmustafa Pile-up/sink-in of rate-sensitive nanoindentation creeping solids , 2007 .

[11]  D. Stone,et al.  Strain rate sensitivity in nanoindentation creep of hard materials , 2007 .

[12]  Zhengxiao Guo,et al.  Multiscale simulation of onset plasticity during nanoindentation of Al (001) surface , 2008 .

[13]  Karin A. Dahmen,et al.  Aluminum Alloying Effects on Lattice Types, Microstructures, and Mechanical Behavior of High-Entropy Alloys Systems , 2013 .

[14]  U. Glatzel,et al.  Phase separation in equiatomic AlCoCrFeNi high-entropy alloy. , 2013, Ultramicroscopy.

[15]  B. Li,et al.  Microstructure and compressive properties of AlCrFeCoNi high entropy alloy , 2008 .

[16]  The anisotropic work-hardening of WC crystals , 1992 .

[17]  J. Yeh,et al.  Effects of Al addition on the microstructure and mechanical property of AlxCoCrFeNi high-entropy alloys , 2012 .

[18]  F. Roters,et al.  Orientation dependence of nanoindentation pile-up patterns and of nanoindentation microtextures in copper single crystals , 2004 .

[19]  T. Nieh,et al.  Incipient plasticity and dislocation nucleation of FeCoCrNiMn high-entropy alloy , 2013 .

[20]  J. Yeh,et al.  Phases, microstructure and mechanical properties of AlxCoCrFeNi high-entropy alloys at elevated temperatures , 2014 .

[21]  H. Tsai,et al.  Evolution of microstructure, hardness, and corrosion properties of high-entropy Al0.5CoCrFeNi alloy , 2011 .

[22]  Anna M. Manzoni,et al.  High-Temperature Tensile Strength of Al10Co25Cr8Fe15Ni36Ti6 Compositionally Complex Alloy (High-Entropy Alloy) , 2015 .

[23]  B. S. Murty,et al.  Formation and Stability of Equiatomic and Nonequiatomic Nanocrystalline CuNiCoZnAlTi High-Entropy Alloys by Mechanical Alloying , 2010 .

[24]  Joost J. Vlassak,et al.  Measuring the elastic properties of anisotropic materials by means of indentation experiments , 1994 .

[25]  W. Clegg,et al.  Deformation underneath low-load indentations in copper , 2008 .

[26]  John C. Horwath,et al.  Magnetic and vibrational properties of high-entropy alloys , 2011 .

[27]  D. H. Wen,et al.  Nanoindentation creep behavior in a CoCrFeCuNi high-entropy alloy film with two different structure states , 2015 .

[28]  Michael D. Uchic,et al.  Exploration and Development of High Entropy Alloys for Structural Applications , 2014, Entropy.

[29]  Jien-Wei Yeh,et al.  Microstructure and texture evolution during annealing of equiatomic CoCrFeMnNi high-entropy alloy , 2014 .

[30]  J. Yeh,et al.  Effect of the aluminium content of AlxCrFe1.5MnNi0.5 high-entropy alloys on the corrosion behaviour in aqueous environments , 2008 .

[31]  G. Pharr,et al.  An improved technique for determining hardness and elastic modulus using load and displacement sensing indentation experiments , 1992 .

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

[33]  A. Elmustafa,et al.  A numerical study on pile-up in nanoindentation creep , 2008 .

[34]  D. Tabor A simple theory of static and dynamic hardness , 1948, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences.

[35]  H. J. Yang,et al.  Nanoindentation characterised plastic deformation of a Al0.5CoCrFeNi high entropy alloy , 2015 .

[36]  Fuqian Yang,et al.  Nanoindentation deformation of a bi-phase AlCrCuFeNi2 alloy , 2014 .

[37]  J. Yeh,et al.  Microstructure and mechanical property of as-cast, -homogenized, and -deformed AlxCoCrFeNi (0 ≤ x ≤ 2) high-entropy alloys , 2009 .

[38]  Jing Shi,et al.  Microstructure and mechanical properties of CoCrFeNiTiAlx high-entropy alloys , 2009 .

[39]  R. Pippan,et al.  Microstructural investigation of the volume beneath nanoindentations in copper , 2007 .