Microstructure of bonding zones in laser-clad Ni-alloy-based composite coatings reinforced with various ceramic powders

Journal Article · Thu Feb 01 00:00:00 EST 1996 · Metallurgical Transactions, A

DOI:https://doi.org/10.1007/BF02648416· OSTI ID:207689

Pei, Y T ^[1]; Ouyang, J H; Lei, T C ^[2]

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1. Beijing Polytechnic Univ. (China). Dept. of Materials Science and Engineering
2. Harbin Inst. of Tech. (China). Dept. of Metals and Technology

Microstructure of the bonding zones (BZs) between laser-clad Ni-alloy-based composite coatings and steel substrates was studied by means of scanning electron microscope (SEM) and transmission electron microscope (TEM) techniques. Observations indicate that for pure Ni-alloy coating the laser parameters selected for good interface fusion have no effect on the microstructure of the BZ except for its thickness. However, the addition of ceramic particles (TiN, SiC, or ZrO{sub 2}) to the Ni alloy varies the compositional or constitutional undercooling of the melt near the solid/liquid interface and consequently leads to the observed changes of microstructure of the BZs. For TiN/Ni-alloy coating the morphology of {gamma}-Ni solid solution in the BZ changes from dendritic to planar form with increasing scanning speed. A colony structure of eutectic is found in the BZ of SiC/Ni-alloy coating in which complete dissolution of SiC particles takes place during laser cladding. The immiscible melting of ZrO{sub 2} and Ni-alloy powders induces the stratification of ZrO{sub 2}/Ni-alloy coating which consists of a pure ZrO{sub 2} layer fin the upper region and a BZ composed mainly of {gamma}-Ni dendrites adjacent to the substrate. All the BZs studied in this investigation have good metallurgical characteristics between the coatings and the substrates.

• Sponsoring Organization: USDOE
• OSTI ID: 207689
• Journal Information: Metallurgical Transactions, A, Vol. 27, Issue 2; Other Information: PBD: Feb 1996
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COMPOSITE MATERIALS
ENERGY BEAM DEPOSITION
MICROSTRUCTURE
NICKEL BASE ALLOYS
CHROMIUM ALLOYS
BORON ALLOYS
SILICON ALLOYS
IRON ALLOYS
SILICON CARBIDES
TITANIUM NITRIDES
ZIRCONIUM OXIDES
YTTRIUM OXIDES
CARBON ADDITIONS
STEELS
SCANNING ELECTRON MICROSCOPY
TRANSMISSION ELECTRON MICROSCOPY
INTERFACES
SOLID SOLUTIONS
DENDRITES
EUTECTICS
MELTING