Rapid Nitriding of Titanium Alloy with Fine Grains at Room Temperature.

Multifunctional surfaces are required to design safe engineering products for human lives. Heating in a nitrogen atmosphere (nitriding) improves the tribological properties but reduces the strength of titanium (Ti) alloys owing to grain coarsening. A rapid nitriding method for Ti alloys forms the nitrided layer on the surface of a Ti alloy by bombarding with commercially pure Ti fine particles with a nitrided phase at room temperature within a short period. Furthermore, fine grains of Ti alloy are formed in the nitrided layer because of the impact of the Ti particles. These results reveal that this room-temperature method resolves the trade-off between the rapid formation of a nitrided layer and the suppression of grain coarsening for Ti alloys.