Welding of high-entropy alloys and compositionally complex alloys—an overview

Abstract

High-entropy alloys (HEAs) and compositionally complex alloys (CCAs) represent new classes of materials containing five or more alloying elements (concentration of each element ranging from 5 to 35 at. %). In the present study, HEAs are defined as single-phase solid solutions; CCAs contain at least two phases. The alloy concept of HEAs/CCAs is fundamentally different from most conventional alloys and promises interesting properties for industrial applications (e.g., to overcome the strength-ductility trade-off). To date, little attention has been paid to the weldability of HEAs/CCAs encompassing effects on the welding metallurgy. It remains open whether welding of HEAs/CCAs may lead to the formation of brittle intermetallics and promote elemental segregation at crystalline defects. The effect on the weld joint properties (strength, corrosion resistance) must be investigated. The weld metal and heat-affected zone in conventional alloys are characterized by non-equilibrium microstructural evolutions that most probably occur in HEAs/CCAs. The corresponding weldability has not yet been studied in detail in the literature, and the existing information is not documented in a comprehensive way. Therefore, this study summarizes the most important results on the welding of HEAs/CCAs and their weld joint properties, classified by HEA/CCA type (focused on CoCrFeMnNi and AlxCoCrCuyFeNi system) and welding process.

Influence of Surface Preparation on Cracking Phenomena in TIG-Welded High and Medium Entropy Alloys

“…With a total of over 100 publications in 2021, the knowledge about weldability of HEAs is steadily increasing [11,12]. However, the practical welding processing of this alloy type is still largely unexplored.…”

“…Meanwhile, it is established that CoCrFeMnNi HEAs have good weldability for fusion welding processes such as laser beam (LB), electron beam (EB), or tungsten inert-gas (TIG) welding [11]. The reason for the good weldability of CoCrFeMnNi HEAs is that no cracks or other weld imperfections, which are material related, have been described so far in the literature [13,16,17].…”

Wire and Arc Additive Manufacturing of a CoCrFeMoNiV Complex Concentrated Alloy Using Metal-Cored Wire—Process, Properties, and Wear Resistance

“…One limiting factor is the lack of knowledge about the welding or additive manufacturing and the influence of these processes on the properties of the CCAs [30]. Another limiting factor of this additive manufacturing process is the availability of the used wireshaped filler materials.…”

Welding Techniques for High Entropy Alloys: Processes, Properties, Characterization, and Challenges

“…Defects are, of course, still possible with this technique. Contamination, tunneling, and incomplete penetration of the joined metals are examples of such possible defects [ 50 ]. However, all these defects can be mitigated by optimizing the welding parameters.…”

“…Weldability and integrity are two important factors considered during welding for a particular application. The welding of similar and dissimilar HEAs expands their applications and makes them a versatile category of materials for structural and functional applications [ 48 , 49 , 50 ]. Each welding technique has its characteristic properties, and they differ in mechanism, welding parameters, joint preparation, filler wires, inert gas, and substrate thickness [ 51 , 52 ].…”