Ultrastrong ductile and stable high-entropy alloys at small scales

Abstract

Refractory high-entropy alloys (HEAs) are a class of emerging multi-component alloys, showing superior mechanical properties at elevated temperatures and being technologically interesting. However, they are generally brittle at room temperature, fail by cracking at low compressive strains and suffer from limited formability. Here we report a strategy for the fabrication of refractory HEA thin films and small-sized pillars that consist of strongly textured, columnar and nanometre-sized grains. Such HEA pillars exhibit extraordinarily high yield strengths of ∼10 GPa—among the highest reported strengths in micro-/nano-pillar compression and one order of magnitude higher than that of its bulk form—and their ductility is considerably improved (compressive plastic strains over 30%). Additionally, we demonstrate that such HEA films show substantially enhanced stability for high-temperature, long-duration conditions (at 1,100 °C for 3 days). Small-scale HEAs combining these properties represent a new class of materials in small-dimension devices potentially for high-stress and high-temperature applications.

High‐Entropy Alloy (HEA)‐Coated Nanolattice Structures and Their Mechanical Properties

“…[41,[45][46][47] Furthermore, scaling down a material structure down to the nanoscale can cause them to exhibit different behaviors, as compared to their bulk counterparts, in which they become stronger as their size is reduced according to the Hall-Petch relationship. [23,48,49] Therefore, it is hypothesized that a thin HEA film at nanoscale may greatly enhance the mechanical performance of the composite micro/nano structure. It is, therefore, recognized that the unique superior performance of our composite nanolattice can be ascribed to the thin HEA film with promising mechanical performance at nanoscale and the "size effect" of the structural geometry size.…”

“…[30,31] For example, Zou et al proved that the HEA at nanoscale exhibit extraordinarily high tensile strength and ductility compared to its bulk form. [23] Unfortunately, to date, no prior research pertaining to 3D nano/micro lattice in combination with nanoscale HEA has been reported yet. However, with the rapid advancement of sputtering techniques, HEA film fabricated at nanoscale can now be employed as the optimal coating material.…”

“…However, with the rapid advancement of sputtering techniques, HEA film fabricated at nanoscale can now be employed as the optimal coating material. [23,32,33] Likewise, Lee et al has used the sputtering technique to successfully manufacture metallic glass nanolattices. [19] Additionally, the flexibility of two-photon lithography (TPL) allows countless number of different lattices with several orders of hierarchy and sizes to be fabricated.…”

“…[21][22][23][24][25] HEAs characteristic feature of entropy maximization to achieve phase stabilization allows them to obtain unique microstructures and exhibit promising properties. [26][27][28] CoCrFeNiAl 0.3 HEA fiber fabricated by Li et al exhibited an outstanding combination of strength and ductility, providing an innovative way to fabricate high performance engineering materials.…”

Nanostructured multielement (TiHfZrNbVTa)N coatings before and after implantation of N+ ions (1018cm−2): Their structure and mechanical properties

“…Nitride coatings from HEA have received particular attention because of improved physical and mechanical characteristics. Most of HEA nitrides consist of 5, 6 or 7 elements, but they can incorporate up to 19 elements [38][39][40][41][42][43][44][45] resistance remains still largely unexplored. For the last few years several papers, devoted to the influence of Cu -, Au -, N + ion implantation on hardness, plasticity index and corrosion resistance were published [46][47][48][49][50].…”