Laser surface alloying fabricated porous coating on
NiTi shape memory alloy
NiTi shape memory alloy
(1. School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110023, China;
2. School of Materials and Metallurgy, Northeastern University,
Shenyang 110023, China;
3. Department of Industrial Systems Engineering, Hongkong Polytechnic University, Kowloon, Hongkong)
2. School of Materials and Metallurgy, Northeastern University,
Shenyang 110023, China;
3. Department of Industrial Systems Engineering, Hongkong Polytechnic University, Kowloon, Hongkong)
Abstract: Laser surface alloying technique was applied to fabricate a metallic porous coating on a solid NiTi shape memory alloy. By laser surface alloying a 40%TiH2-60%NiTi powder mixture on the surface of NiTi alloy using optimized laser process parameters, a porous but crack-free NiTi layer can be fabricated on the NiTi substrate. The porous coating is metallurgically bonded to the substrate NiTi alloy. The pores are uniformly distributed and are interconnected with each other in the coating. An average pore size of less than 10 μm is achieved. The Ni content of the porous layer is much less than that of the original NiTi surface. The existence of the porous coating on the NiTi alloy causes a 37% reduction of the tensile strength and 55% reduction of the strain as compared with the NiTi alloy. Possible biomedical or other applications for this porous surface with good mechanical strength provided by the substrate are prospective.
Key words: laser surface alloying; NiTi shape memory alloy; porous coating; biomaterial