Laser surface alloying (LSA) is a process that uses a high-energy laser beam to melt a thin surface layer of a material and mix it with alloying elements to modify the surface properties. The laser system focuses and directs the beam onto the material's surface, creating a localized melting zone. Alloying elements are then introduced into the molten pool, where they diffuse into the material and solidify to form a homogenized alloyed layer with improved properties like hardness and corrosion resistance. By controlling laser parameters and alloy composition, LSA can tailor surfaces for applications in automotive, aerospace, and cutting tools.

1. Course code CME397 Course name Surface Engineering
Year/sem 3/6 Unit no 4
Course Instructor: M.Karthikeyan AP/Mech
Laser surface alloying (LSA)
Laser surface alloying (LSA) is a process used to modify the surface properties
of materials by melting a thin layer using laser and mixing it with one or more
alloying elements
1. Laser System:
The heart of laser surface alloying is the laser system itself.
It typically consists of a laser source, such as a CO2 laser, Nd:YAG
laser, or fiber laser, which emits a high-energy beam of light.
The laser system also includes optics for focusing and directing the
laser beam onto the surface of the material to be treated.
2. Material Preparation:
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2. Before the alloying process, the surface of the material is prepared by
cleaning and preheating it to remove contaminants and ensure proper
adhesion of the alloying elements.
3. Alloying Elements:
Alloying elements are often in the form of powders or wires.
These elements are chosen based on the desired properties of the
alloyed surface, such as improved hardness, wear resistance, corrosion
resistance, or other specific characteristics.
4. Surface Irradiation:
The focused laser beam is directed onto the surface of the material,
creating a localized melting zone.
The high energy of the laser beam rapidly heats the surface to
temperatures above the melting point of the base material.
5. Alloying Process:
Simultaneously or immediately after the surface is melted, the alloying
elements are introduced into the molten pool either through powder
injection or by feeding a wire into the melt zone.
The intense heat of the molten surface causes the alloying elements to
diffuse into the base material, forming a homogenized alloyed layer.
6. Cooling and Solidification:
Once the alloying process is complete, the laser beam is moved away,
and the molten pool rapidly cools and solidifies.
The rapid cooling rate often results in a fine microstructure, which can
contribute to the improved mechanical properties of the alloyed surface.
7. Post-Processing:
After solidification, the alloyed surface may undergo additional
treatments such as quenching or tempering to further refine its
microstructure and enhance its properties.

3. The working principle of laser surface alloying relies on precise control of laser
parameters such as power, spot size, scanning speed, and alloying element
composition.
By carefully adjusting these parameters, engineers can tailor the properties
of the alloyed surface to meet specific requirements for different applications,
including automotive components, aerospace parts, cutting tools, and more.