Study on improving the surface hardness of TiAl alloy by laser nitriding in an atmospheric ambient

Laser nitridation in an atmospheric ambient was applied to improve the surface hardness of Titanium alloy. The samples were nitrided with laser power density of 6.5×105 w.cm-2, the scanning speed of 100mm.min-1. The nitrogen gas was pre-heated to 300oC to accelerate the nitriding process. Some interested samples were tested with XRD method to analyze the composition of nitrides, and the surface hardness of HV was measured. The results show that TiN and Ti2N were formed on the surface of Ti alloy with proper nitriding parameters, but TiN is the main composition. The surface hardness increased by three times, that is from the original value of 269 Kg.mm-2 to 794Kg.mm-2.