Definition - What does Laser Alloying mean?
Laser alloying is a material processing method which utilizes focused laser sources to melt metal coatings and a portion of the underlying substrate, causing fusing and alloying.
Laser alloying produces surfaces with desirable properties on relatively low-cost substrate materials. It can produce a stainless-steel surface on low-carbon steel by alloying nickel and chromium, for example.
Although laser alloying has considerable promise and research interest, it is not currently in widespread use.
Corrosionpedia explains Laser Alloying
Laser alloying is a surface modification technology in which the alloying elements are deposited on the substrate surface and then irradiated by a high-energy laser beam. This causes rapid melting and mixing, so that the alloy elements and ceramic materials disperse. In a very short period of time, cooling and solidification form a thickness of 0.1-0.5mm of a new alloy layer. This alloy layer and the substrate have strong binding force, high hardness and good wear resistance.
Laser surface alloying is attractive because of the wide variety of chemical and microstructural states that can be retained because of the rapid quench from the liquid phase. These include chemical profiles where the alloyed element is highly concentrated near the atomic surface and decreases in concentration over shallow depths (hundreds of nanometers), and uniform profiles where the concentration is the same throughout the entire melted region.
Many factors must be considered in the laser alloying process. These include:
- Exposure time
- Laser power
- Thickness of the film
- Nature of the gaseous ambient during laser processing
The processing variables are interrelated, and one variable cannot be freely changed without affecting another. Another consideration is that laser alloying is a liquid-state, rapid-quenching phenomenon. The near-surface region must be melted and yet vaporization avoided.
Laser alloying also involves very large temperature gradients and quenching from the liquid state. In this way it resembles other rapid-solidification technologies.