High Entropy Alloys as Filler Metals for Joining

Abstract

In the search for applications for alloys developed under the philosophy of the High Entropy Alloy (HEA)-type materials, the focus may be placed on applications where current alloys also use multiple components, albeit at lower levels than those found in HEAs. One such area, where alloys with complex compositions are already found, is in filler metals used for joining. In soldering (<450 °C) and brazing (>450 °C), filler metal alloys are taken above their liquidus temperature and used to form a metallic bond between two components, which remain both unmelted and largely unchanged throughout the process. These joining methods are widely used in applications from electronics to aerospace and energy, and filler metals are highly diverse, to allow compatibility with a broad range of base materials (including the capability to join ceramics to metals) and a large range of processing temperatures. Here, we review recent developments in filler metals relevant to High Entropy materials, and argue that such alloys merit further exploration to help overcome a number of current challenges that need to be solved for filler metal-based joining methods.

RETRACTED: Laser Welding of UNS S33207 Hyper-Duplex Stainless Steel to 6061 Aluminum Alloy Using High Entropy Alloy as a Filler Material

“…These different regions were: a linear elastic area, a tiny plastic region, and a further linear elastic region followed by plastic deformation [65]. As previously observed, coarse columnar grains in the joint region resulted in poorer ductility than fine equiaxed refined microstructure [66,67]. The Vicker's microhardness profile for the joint cross-section is given in Figure 13.…”

Recent Advances in Brazing Fillers for Joining of Dissimilar Materials

“…The brazing filler is melted above its liquidus temperature, which wets the contact surfaces and often flows between the components to be joined (step 4). In the final step, the filler cools, solidifies, and bonds the components (step 5) [2,13,14]. necessary before brazing.…”

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

“…Weldability studies, which contain data on filler metals for welding of HEAs or use them as filler metals, are rare. Publications on brazing/ soldering [43] or fusion welding [44] can be found but are out of the scope of the present overview. The problem is that the nearly equiatomic composition must be guaranteed.…”