Welding of unique and advanced ductile intermetallic alloys for high-temperature applications

Abstract

Intermetallic alloys represent a unique class of materials with atomic arrangements that are different from those of conventional disordered alloys. Among them are alloys based on Ni₃Al, Fe₃Al, and TiAl. Intermetallic alloys have unique properties, such as high melting point, low density, high-temperature strength, and high-temperature corrosion and oxidation resistance. Their only disadvantage is the lack of ductility at room temperature and at elevated temperatures. However, they can be ductilised by micro- and macroalloying. Application of intermetallic alloys for structural use at elevated temperature depends on their ability to be welded using conventional welding procedures. This paper focuses on the development of these alloys, their behaviour when subjected to weld thermal cycles, and their weldability. Most intermetallic alloys are susceptible to cracking during or after welding, but some can be modified to have good weldability. The paper discusses welding and weldability of Ni₃Al-, Fe₃Al-, and TiAl-based intermetallic alloys. In addition, the weldability of other long-range ordered alloys, of the type (Fe, Ni)₃V and (Fe, Co)₃V, are briefly discussed.