Superficial treatments using high-energy-density beams

In the evolution of modern materials, multi-materials hold a privileged place because they enable incompatible properties to be reconciled in a single material. They are also often the source of substantial cost savings. However, it is often through localized or surface treatments that high-performance multimaterials can be created.

Over the years, the share of surface heat treatments has steadily risen in relation to that of in-situ treatments (40% forecast in 2000, compared with an estimated 10% in 1975).

The power densities (or laser intensities) available from the sources used for surface treatment of materials are as follows:

• Burning flashlight: 1.5 × 10 ³ W/cm ²

• Induction: 2.5 × 10 ⁴ W/cm ²

• Arc melting: 5 × 10 ⁴ to 10 ⁶ W/cm ²

• Plasma: 5 × 10 ⁴ to 10 ⁸ W/cm ²

• Laser beam and electron beam: 10 ⁸ to 10 ¹⁰ W/cm ²

Among the techniques used for surface heat treatment, the most recent uses high energy density FHDE beams (laser and electron beams).

The possibilities for using these sources abound, as their use reduces the risk of deformation, and enables high productivity and flexibility, particularly in the case of lasers, where beam control by appropriate optical systems makes it possible to treat areas that are difficult to access by other processes.

Thanks to the extreme power involved, short thermal cycles enable the creation of new, original structures that are difficult or impossible to achieve by other means.

However, while a great deal of research is being undertaken, industrial applications are rarer .