Laser Induced Surface Modification of Aluminum Alloys
Laser induced surface modification (LISM) is a process developed under the
main theme of laser induced reaction processing which include coating, alloying
and joining of materials. LISM in particular is a material processing method
which utilizes the high power density available from laser sources to heat the
precursor to a temperature below or above melting and a portion of the
underlying substrate material to the melting temperature to produce in-situ
reaction product. Since melting occurs rapidly and only at the surface and
subsurface, the bulk of the material remains cool, thus creating rapid
self-quenching and solidification. The wide variety of chemical and
microstructural states can be retained because of the rapid quench from the
liquid phase. These include chemical profiles where the alloyed element or
infiltrated reinforcement material is highly concentrated near the atomic
 surface and decreases in concentration over shallow depths, and uniform profiles
where the concentration is the same throughout the entire modified region. These
types of microstructures range from solid solutions with distinct crystalline
phases to metallic glasses. Currently, initial efforts are being directed toward
modifying structural aluminum (7xxx, 6xxx and 2xxx series) surfaces for enhanced
fatigue and wear properties using LISM.
Investigator: Dr. N.B. Dahotre
Sponsor: Aluminum Company of America (ALCOA)
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