Laser and Electron-Beam Surface Processing on NiTi Shape Memory Alloys: A Review.

The review summarizes the progress achieved in the surface modification of NiTi shape memory alloys (SMAs) with laser and electron beams in terms of their compliance with the requirements for biomedical devices and implants. The main provisions of the standards regulating this area of activity are aggregated. The production routes for manufacturing bulk items from NiTi SMAs are described. Since the formation of surface alloys on NiTi SMAs is now an intensively growing area of research, the influence of additional alloying elements on their functional properties is also discussed. The common patterns of interaction of laser and electron radiation with NiTi SMAs are specified. The typical requirements for surface layer conditions and conventional methods for their modification are reported. The results of various laser processing methods, differing in energy parameters, atmospheres and beam scanning algorithms, are summarized. They include remelting, annealing, nitriding, shock peening, alloying and texturing. In addition, some data on the modification and alloying of the surface layers with high-current pulsed electron beams are integrated. Finally, the aggregated information is compared and analyzed from the point of view of its prospects in these research areas. [ABSTRACT FROM AUTHOR]