Development of a Refractory High Entropy Superalloy

By Oleg N. Senkov, Dieter Isheim, David N. Seidman, Adam L. Pilchak. Entropy, 2016

297 citations recorded by the source corpus.

Microstructure, phase composition and mechanical properties of a refractory high entropy superalloy, AlMo0.5NbTa0.5TiZr, are reported in this work. The alloy consists of a nano-scale mixture of two phases produced by the decomposition from a high temperature body-centered cubic (BCC) phase. The first phase is present in the form of cuboidal-shaped nano-precipitates aligned in rows along -type directions, has a disordered BCC crystal structure with the lattice parameter a1 = 326.9 ± 0.5 pm and is rich in Mo, Nb and Ta. The second phase is present in the form of channels between the cuboidal nano-precipitates, has an ordered B2 crystal structure with the lattice parameter a2 = 330.4 ± 0.5 pm and is rich in Al, Ti and Zr. Both phases are coherent and have the same crystallographic orientation within the former grains. The formation of this modulated nano-phase structure is discussed in the framework of nucleation-and-growth and spinodal decomposition mechanisms. The yield strength of this refractory high entropy superalloy is superior to the yield strength of Ni-based superalloys in the temperature range of 20 °C to 1200 °C.

Subfields: Aerospace Engineering, Biomedical Engineering, Mechanical Engineering

View Paper: https://www.semanticscholar.org/paper/327a5de7d23e7a1c9f39d85fe671313248cecec7

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Citations in the corpus

Controlled formation of coherent cuboidal nanoprecipitates in body-centered cubic high-entropy alloys based on Al2(Ni,Co,Fe,Cr)14 compositions (2018, background): “5TiZr HEA, cuboidal BCC particles were observed to coherently embed in the B2 matrix, besides some plate-like BCC precipitates [27].”
High-entropy alloys fabricated via powder metallurgy. A critical review (2019, background): “These HEAs are called ‘refractory high-entropy alloys’ [29,178], and were developed in the search for high-temperature loadbearing structures and thermal protection materials”
Development and exploration of refractory high entropy alloys—A review (2018, methodology): “6), due to thermally stable nanoscale precipitation.(48,51) Multiphase AlMo0.”
Mapping the world of complex concentrated alloys (2017, background): “A large variety of morphologies are seen, arising from phase transformations that include order/disorder transformation [5, 6], spinodal decomposition [7-10], precipitation [4, 11, 12] and massive transformation [13, 14].”
A critical review of high entropy alloys and related concepts (2016, methodology): “The microstructure was initially reported as modulated nanolamellae of two BCC phases [94], but detailed three-dimensional tomographic characterization via TEM dark field imaging later showed this to be BCC cuboids roughly 50 nm on a side surrounded by B2 nano-lamellae parallel to the cuboid faces [”