Joining of nickel monoaluminide to a superalloy substrate by high pressure self-propagating high-temperature synthesis

• Published in: Journal of alloys and compounds Vol. 337; no. 1-2; pp. 221 - 225
• Main Authors: Pascal, C, Marin-Ayral, R.M, Tédenac, J.C
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 02.05.2002; Elsevier
• Subjects: Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; High temperature alloys; Intermetallics; Materials science; Materials synthesis; materials processing; Physics; Powder metallurgy; Powder processing: powder metallurgy, compaction, sintering, mechanical alloying, and granulation; SEM; Intermetallics; High temperature alloys; SEM; Powder metallurgy; Powders; Inorganic compounds; Pressure effects; Melting; Nickel alloys; Intermetallic compounds; Welding; Phase transformations; Joining; Self propagating high temperature synthesis; Melting points; Superalloys; Heat treatments; Contact surface; Interfaces; Aluminium alloys; Powder compaction; Diffusion; Heat transfer; Transition element alloys
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/S0925-8388(01)01924-7

A parallelepipedic nickel monoaluminide (NiAl) has been synthesised by self-propagating high-temperature synthesis (SHS) from an equimolar mixture of nickel and aluminium powders and simultaneously joined to a superalloy substrate with the same shape. By heating the joining couple (compact (Ni+Al)/superalloy substrate) to approximately 920 K, an exothermic reaction synthesis, Ni+Al→NiAl, spontaneously starts and propagates along the powder compact. The temperature of the compact quickly rises owing to the heat of the reaction and reaches the melting temperature of NiAl (1950 K) in adiabatic conditions. The heat transfer provides the superficial melting of the substrate which wetted the contact surfaces and partially dissolved the NiAl compound. In such conditions, an aluminium-rich nickel base superalloy has been produced at the interface. The SHS joining process can be referred to as exothermic welding. This process involves different metallurgical phenomena such as fusion, dissolution, diffusion and solidification.