Laser Surface Modifications of Superalloys for Enhanced Bonding
 Under the one-year sponsorship of Babcock & Wilcox, an autogeneous laser
surface treatment of nickel based alloy 690 for enhanced diffusion bonding was
developed. Alloy 690 was laser surface scanned using pulsed Nd-Yag laser to
homogenize and refine the microstructure within the surface and subsurface
region. Rapid cooling rate involved in the process provided metastable
structures which in turn modified the diffusion kinetics during the post laser
treatment diffusion bonding of the alloy 690. The modified diffusion kinetics
allowed to conduct the bonding process at temperature 200oC less and with
duration 2 hours less compared to diffusion bonding for as received alloy. Such
savings in time and temperature provide an economical process for commercial
environment and can be extended to variety of high temperature materials.
Investigator: Dr. N.B. Dahotre
Sponsor: Department of Energy
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