Laser cladding of Ni-Cr-Al-Hf on inconel 718 for improved high-temperature oxidation resistance
In-situ Ni-Cr-Al-Hf alloy was developed by laser surface cladding with a mixed-powder feed for improved high-temperature oxidation resistance. Oxidation-resistant materials for operation at elevated temperatures must satisfy two requirements: diffusion through the oxide scale must occur at the lowest possible rate, and the oxide scale must resist spallation. Formation of an Al/sub 2/O/sub 3/ protective scale fulfills the former requirement but its adherence is poor. A reactive metal such as Hf is added to improve adhesion. A 10-kW CO/sub 2/ laser was used for laser cladding. Optical, SEM and STEM microanalysis techniques were employed to characterize the different phases produced during the cladding process. Microstructural studies showed a high degree of grain refinement, increased solid solubility of Hf in the matrix and the formation of Hf-rich precipitates. A thermogravimetric analysis was carried out to determine the oxidation properties of these clad alloys with an extended solid solution of Hf. Considerable improvement over the base metal was observed. This paper discusses microstructural development in this laser-clad alloy and its effect on oxidation.
- Research Organization:
- Illinois Univ., Urbana (USA). Laser Aided Materials Processing Lab.
- OSTI ID:
- 7146224
- Report Number(s):
- AD-A-192450/5/XAB; LAMP-AF-04
- Resource Relation:
- Other Information: Pub. in High Temperature Technology, Vol. 5, No. 3, 131-138(Aug 1987)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ALUMINIUM ALLOYS
CLADDING
CHROMIUM ALLOYS
HAFNIUM ALLOYS
INCONEL 718
PROTECTIVE COATINGS
NICKEL ALLOYS
ADHESION
FEEDING
HIGH TEMPERATURE
METALS
MICROSTRUCTURE
MIXING
OPERATION
OXIDATION
OXIDES
POWDERS
REFINING
SOLID SOLUTIONS
SOLIDS
SOLUBILITY
SPALLATION
SURFACES
ALLOYS
CHALCOGENIDES
CHEMICAL REACTIONS
COATINGS
CRYSTAL STRUCTURE
DEPOSITION
DISPERSIONS
ELEMENTS
INCONEL ALLOYS
MIXTURES
MOLYBDENUM ALLOYS
NICKEL BASE ALLOYS
NIOBIUM ALLOYS
NUCLEAR REACTIONS
OXYGEN COMPOUNDS
PROCESSING
SOLUTIONS
SURFACE COATING
360105* - Metals & Alloys- Corrosion & Erosion
360101 - Metals & Alloys- Preparation & Fabrication