Title: Transient liquid phase bonding of structural intermetallic compounds

Authors: W.F. Gale, Y. Guan, S.V. Orel

Addresses: Materials Research and Education Center, Auburn University, Auburn, AL 36849, USA. ' Materials Research and Education Center, Auburn University, Auburn, AL 36849, USA. ' Applied Materials Inc., Austin, TX 78724, USA

Abstract: The intermetallic compound NiAl is a candidate material for high-temperature structural applications, for example in the hot-zone of aero gas turbine engines. However, if this material is to find significant structural applications, methodologies for primary fabrication of complex components and post-service repair will be required. In particular, joining technologies suitable for bonding NiAl to nickel-base alloys are required. This paper examines transient liquid phase (TLP) bonding as a method of joining NiAl to nickel-base alloys. The focus of the paper is microstructural development at the bond-line and in the adjacent (nickel-base and NiAl) substrates. Two different interlayer materials are considered in this paper, namely: Ni – 4.5 wt.% Si – 3.2 wt.%B (designated by the American Welding Society as |BNi-3|) and commercially pure copper. Bonds between binary, nominally-stoichiometric NiAl and both commercially pure nickel and Martin Marietta 247 are examined using edge-on transmission electron microscopy. The paper considers the character of the isothermal solidification process, the formation of second-phases at the bond-line and in the adjacent substrates and the extent to which NiAl-Ni-base alloy TLP bonds obey the assumptions implicit in standard models of the TLP process.

Keywords: superalloy bonding; nickel aluminides; structural intermetallic compounds; transient liquid phase; TLP bonding; nickel; aluminium; copper; silicon; gas turbine engines; aero engines; microstructure; isothermal solidification.

DOI: 10.1504/IJMPT.1998.036224

International Journal of Materials and Product Technology, 1998 Vol.13 No.1/2, pp.1 - 12

Published online: 01 Nov 2010 *

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