Laser metal deposition of compositionally graded TiZrNbTa refractory high-entropy alloys using elemental powder blends

Abstract In the present study, laser metal deposition (LMD) was used to produce compositionally graded refractory high-entropy alloys (HEAs) for screening purposes by in-situ alloying of elemental powder blends. A compositional gradient from Ti25Zr50Nb0Ta25 to Ti25Zr0Nb50Ta25 is obtained by incrementally substituting Zr powder with Nb powder. A suitable strategy was developed to process the powder blend despite several challenges such as the high melting points of the refractory elements and the large differences in melting points among them. The influence of the LMD process on the final chemical composition was analyzed in detail and the LMD process was optimized to obtain a well-defined compositional gradient. Microstructures, textures, chemical compositions and mechanical properties were characterized using SEM, EBSD, EDX, and microhardness testing, respectively. Compositions between Ti25Zr0Nb50Ta25 and Ti25Zr25Nb25Ta25 were found to be single-phase bcc solid solutions with a coarse grain microstructure. Increasing the Zr to Nb ratio beyond the equiatomic composition results in finer and harder multiphase microstructures. The results shown in the present study clearly show for the first time that LMD is a suitable processing tool to screen HEAs over a range of chemical compositions.

[1]  N. Stepanov,et al.  Aging behavior of the HfNbTaTiZr high entropy alloy , 2018 .

[2]  William A. Curtin,et al.  Atomistic simulations of dislocations in a model BCC multicomponent concentrated solid solution alloy , 2016 .

[3]  A. Weisheit,et al.  Combining thermodynamic modeling and 3D printing of elemental powder blends for high-throughput investigation of high-entropy alloys – Towards rapid alloy screening and design , 2017 .

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

[5]  I. Guillot,et al.  Elastic and plastic properties of as-cast equimolar TiHfZrTaNb high-entropy alloy , 2016 .

[6]  Peter C. Collins,et al.  Direct laser deposition of alloys from elemental powder blends , 2001 .

[7]  Structural anomaly in the high-entropy alloy ZrNbTiTaHf , 2016 .

[8]  E. George,et al.  Elastic moduli and thermal expansion coefficients of medium-entropy subsystems of the CrMnFeCoNi high-entropy alloy , 2018 .

[9]  I. Guillot,et al.  Design and tensile properties of a bcc Ti-rich high-entropy alloy with transformation-induced plasticity , 2017 .

[10]  E. George,et al.  Reasons for the superior mechanical properties of medium-entropy CrCoNi compared to high-entropy CrMnFeCoNi , 2017 .

[11]  J. Yeh,et al.  Simultaneously increasing the strength and ductility of a refractory high-entropy alloy via grain refining , 2016 .

[12]  N. Jones,et al.  High-entropy alloys: a critical assessment of their founding principles and future prospects , 2016 .

[13]  E. Eisenbarth,et al.  Biocompatibility of β-stabilizing elements of titanium alloys , 2004 .

[14]  G. K. Lewis,et al.  Practical considerations and capabilities for laser assisted direct metal deposition , 2000 .

[15]  N. Stepanov,et al.  Effect of cryo-deformation on structure and properties of CoCrFeNiMn high-entropy alloy , 2015 .

[16]  M. Heilmaier,et al.  Contribution of Lattice Distortion to Solid Solution Strengthening in a Series of Refractory High Entropy Alloys , 2018, Metallurgical and Materials Transactions A.

[17]  William A. Curtin,et al.  Theory of strengthening in fcc high entropy alloys , 2016 .

[18]  Jian Xu,et al.  (TiZrNbTa)-Mo high-entropy alloys: Dependence of microstructure and mechanical properties on Mo concentration and modeling of solid solution strengthening , 2018 .

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

[20]  I. Guillot,et al.  New structure in refractory high-entropy alloys , 2014 .

[21]  E. George,et al.  Thermal activation parameters of plastic flow reveal deformation mechanisms in the CrMnFeCoNi high-entropy alloy , 2018 .

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

[23]  N. Schell,et al.  Thermodynamic instability of a nanocrystalline, single-phase TiZrNbHfTa alloy and its impact on the mechanical properties , 2018 .

[24]  Gunther Eggeler,et al.  Microstructural evolution of a CoCrFeMnNi high-entropy alloy after swaging and annealing , 2015 .

[25]  Frank W. Liou,et al.  Fabrication and Characterization of AlxCoFeNiCu1−x High Entropy Alloys by Laser Metal Deposition , 2017 .

[26]  E. George,et al.  Tensile properties of high- and medium-entropy alloys , 2013 .

[27]  Jien-Wei Yeh,et al.  Enhanced mechanical properties of HfMoTaTiZr and HfMoNbTaTiZr refractory high-entropy alloys , 2015 .

[28]  Andreas Ostendorf,et al.  Direct Metal Deposition of Refractory High Entropy Alloy MoNbTaW , 2016 .

[29]  Andrew A. Shapiro,et al.  Developing Gradient Metal Alloys through Radial Deposition Additive Manufacturing , 2014, Scientific Reports.

[30]  G. Eggeler,et al.  Microstructure evolution and critical stress for twinning in the CrMnFeCoNi high-entropy alloy , 2016 .

[31]  M. Feuerbacher,et al.  Plastic deformation properties of Zr–Nb–Ti–Ta–Hf high-entropy alloys , 2015 .

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

[33]  Oleg N. Senkov,et al.  Microstructure and properties of a refractory high-entropy alloy after cold working , 2015 .

[34]  K. Chaput,et al.  Compositional effect on microstructure and properties of NbTiZr-based complex concentrated alloys , 2018, Acta Materialia.

[35]  G. Eggeler,et al.  The influences of temperature and microstructure on the tensile properties of a CoCrFeMnNi high-entropy alloy , 2013 .

[36]  Jien-Wei Yeh,et al.  High-Entropy Alloys – A New Era of Exploitation , 2007 .

[37]  Jinghao Li,et al.  Synthesis and characterization of refractory TiZrNbWMo high-entropy alloy coating by laser cladding , 2017 .

[38]  Robert O. Ritchie,et al.  Effect of temperature on the fatigue-crack growth behavior of the high-entropy alloy CrMnFeCoNi , 2017 .

[39]  R. Ritchie,et al.  A fracture-resistant high-entropy alloy for cryogenic applications , 2014, Science.

[40]  Jien-Wei Yeh,et al.  Microstructure and Mechanical Properties of New AlCoxCrFeMo0.5Ni High‐Entropy Alloys , 2010 .

[41]  Haruyuki Inui,et al.  Size effect, critical resolved shear stress, stacking fault energy, and solid solution strengthening in the CrMnFeCoNi high-entropy alloy , 2016, Scientific Reports.

[42]  Thierry Chauveau,et al.  Microstructure of a near-equimolar refractory high-entropy alloy , 2014 .

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

[44]  Jien-Wei Yeh,et al.  Solution strengthening of ductile refractory HfMoxNbTaTiZr high-entropy alloys , 2016 .

[45]  Marc Thomas,et al.  Laser Metal Deposition of the Intermetallic TiAl Alloy , 2017, Metallurgical and Materials Transactions A.