A study on in-situ synthesis of TiCN metal matrix composite coating on Ti–6Al–4V by laser surface alloying process

Laser surface alloying of Ti6Al4V substrate with in-situ synthesized TiCN was carried out by melting preplaced titanium and graphite powders in 3:1 ratio (wt%) in nitrogen atmosphere at different scan speeds in 400–1400 mm/min range, maintaining the laser power and the beam diameter constant at 1200...

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Bibliographic Details
Published in:Journal of alloys and compounds 2019-11, Vol.810, p.151901, Article 151901
Main Authors: Nair, Amal M., Muvvala, Gopinath, Nath, Ashish Kumar
Format: Article
Language:English
Subjects:
Cooling rate
Corrosion resistance
Corrosion tests
Corrosive wear
Dendritic structure
Densification
IR pyrometer
Laser beams
Laser surface alloying
Lasers
Linear polarization
Metal matrix composites
Molten pool thermal history
Organic chemistry
Protective coatings
Scratch tests
Substrates
Surface alloying
Titanium base alloys
Titanium carbonitride
Wear resistance
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Summary:Laser surface alloying of Ti6Al4V substrate with in-situ synthesized TiCN was carried out by melting preplaced titanium and graphite powders in 3:1 ratio (wt%) in nitrogen atmosphere at different scan speeds in 400–1400 mm/min range, maintaining the laser power and the beam diameter constant at 1200 W and 3 mm respectively. Molten pool thermal history during the alloying process was recorded using an IR pyrometer. With the decrease in scan speed, the cooling rate was found to decrease, while the molten pool lifetime increased which caused densification of TiCN dendritic structure. Though it enhanced the hardness, coatings were found to fail exhibiting brittle fracture during the scratch test, while coatings processed at higher scan speeds (800 mm/min −1400 mm/min) were found to be intact. Further, coatings processed at higher scan speeds also exhibited better wear resistance. Linear polarization electro-chemical corrosion test was performed on the coatings and it was observed that even corrosion properties were better in case of coatings processed at higher scan speeds. •Laser surface alloying of Ti6Al4V with in-situ synthesized TiCN is carried out.•Molten pool thermal history monitored by IR pyrometer is correlated with process parameters.•Change in microstructure with molten pool thermal history is reported.•Effect of microstructure on mechanical and corrosion properties is investigated.
ISSN:0925-8388
1873-4669
DOI:10.1016/j.jallcom.2019.151901