High-entropy Al0.3CoCrFeNi alloy fibers with high tensile strength and ductility at ambient and cryogenic temperatures

Abstract

High-entropy alloys (HEAs) are multi-component systems based on novel alloy composition designs with entropy maximization. They feature an array of unique mechanical properties when compared with traditional alloys. In this study, HEA fibers with diameters ranging from 1-3.15 mm in diameter, with the composition of Al 0.3 CoCrFeNi (atomic percent, at. %), were successfully fabricated by hot-drawing, followed by microstructural characterization using scanning-electron microscopy (SEM) and transmission-electron microscopy (TEM). The compositional variations within and between fibers were determined using energy-dispersive X-ray spectroscopy in TEM along with atomic-probe tomography (APT). These analyses revealed a homogeneous face-centered cubic (FCC) structure in the as-cast material, while post processing (e.g., forging and wire drawing) produced nanosized B2 *Text only Click here to download Text only: Text.docx Click here to view linked References

Microstructure, Mechanical and Corrosion Behaviors of CoCrFeNiAl0.3 High Entropy Alloy (HEA) Films

“…Typically, strength is directly proportional to hardness, thus the high hardness value obtained implies the possible high strength of the HEA film [31]. This enhanced hardness is mainly ascribed to the shearing mechanism of dislocated particles or by-pass mechanism (Orowan-type), which induces the hardening produced by the precipitates observed in Figures 2 and 4 [9].…”

“…As a typical case in point, CoCrFeNiAl x family HEA has aroused much attention to date due to its unique properties in terms of its balanced combination of high tensile strength and ductility at ambient or cryogenic temperatures [9,10]. It also exhibits versatile microstructures and other interesting properties compared to conventional alloy systems [2,6,[11][12][13].…”

“…However, the CoCrFeNiAl x HEA fabricated using the conventional vacuum arc melting methodology is always in the bulk solid form. This would be costly, impeding its practicability for real-life applications [2,9,14,15]. Alternatively, it is widely known that thin films can be used as a protective and mechanically enhancing surface coating on the substrate [16][17][18][19][20].…”

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

“…This secondary phase has been identified to be NiAl-type ordered BCC phase by previous study, which is beneficial to the mechanical enhancement of the HEA film due to fact that the NiAl-type BCC phase is much harder than the matrix and presents a barrier to gliding dislocations. [29] Figure 2d is the highresolution transmission electron microscopy (HRTEM) image of the HEA film, which shows the crystallization feature of the HEA film. More importantly, small nanocrystal can be distinctly observed.…”

“…[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. [29] The tensile strength of single phase face-centered cubic (FCC) CrMnFeCoNi HEAs with exceptional damage tolerance was above 1 GPa, and fracture toughness values exceeded 200 MPa m 1/2 . [28] Noted that through reasonably adjusting the dominant structural form, HEA would exhibit alterable mechanical properties, this means.…”