Welding studies of nickel aluminide and nickel-iron aluminides

Technical Report · Thu Aug 01 00:00:00 EDT 1985

OSTI ID:5330917

Santella, M L; David, S A; Horton, J A; White, C L; Liu, C T

Because welding is often used during the fabrication of structural components, one of the key issues in the development of nickel aluminides and nickel-iron aluminides for engineering applications is their weldability. The goals of this study were to characterize weldment microstructures and to identify some of the factors controlling weldability of ductile Ni/sub 3/Al alloys. The alloys used in this initial study were Ni/sub 3/Al containing 500 wppm boron and Ni/sub 3/Al containing 10 at. % iron and either 500 wppm or 20 wppm boron. Full-penetration autogenous welds were made in sheet shock by the electron beam (EB) and gas tungsten arc (GTA) processes. The main process variables were travel speed and preheat. The as-welded coupons were examined visually and in detail by the usual optical and electron metallographic methods. Weldments of boron-doped Ni/sub 3/Al were composed of nearly 100% ordered ..gamma..' phase. Weldments of the nickel-iron aluminides were ..gamma..' + ..beta..' phase mixtures, with martensitic ..beta..' distributed interdendritically in the fusion zone and decorating grain boundaries in the heat-affected zone. All welds made in this particular boron-doped Ni/sub 3/Al alloy contained cracks. Weldability improved with the addition of iron, and defect-free welds were made in the nickel-iron aluminides by both EB and GTA welding. Nevertheless, the iron-containing alloys were susceptible to cracking, and their weldability was affected by boron concentration, welding speed, and (for GTA) gas shielding. Defect-free welds were found to have good tensile properties relative to those of the base metal. 34 refs., 17 figs., 2 tabs.

• Research Organization: Oak Ridge National Lab., TN (USA)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 5330917
• Report Number(s): ORNL-6194; ON: DE85018168
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
MICROSTRUCTURE
TENSILE PROPERTIES
WELDING
IRON ALLOYS
NICKEL ALLOYS
ARC WELDING
AUGER ELECTRON SPECTROSCOPY
BORON ADDITIONS
ELECTRON BEAM WELDING
EXPERIMENTAL DATA
INTERMETALLIC COMPOUNDS
SCANNING ELECTRON MICROSCOPY
ALLOYS
BORON ALLOYS
CRYSTAL STRUCTURE
DATA
ELECTRON MICROSCOPY
ELECTRON SPECTROSCOPY
FABRICATION
INFORMATION
JOINING
MECHANICAL PROPERTIES
MICROSCOPY
NUMERICAL DATA
SPECTROSCOPY
360101* - Metals & Alloys- Preparation & Fabrication
360103 - Metals & Alloys- Mechanical Properties
360102 - Metals & Alloys- Structure & Phase Studies