Amorphization of Ni61Nb39 Alloy by Laser Surface Treatment

The surface of Ni61 Nb39 crystalline ingot was treated by laser surface melting with different processing parameters. A fully amorphous layer with a thickness of approximately 10 μm could be produced on the top surface under optimal parameters. An amorphous-crystalline composite layer with the depth from 10 to 50 μm, consisting of amorphous matrix and intermetallic phases of Ni3Nb and Ni6Nb7, could be formed. The micro-hardness (about 831 HV) of the treated surface was remarkably improved by nearly 100% compared with the value of the crystalline substrate caused by the formation of the fully amorphous structure. A finite volume simulation was adopted to evaluate the temperature distribution in the laser-affected zone of Ni61 Nb39 alloys and to reveal the mechanism of glass formation in the laser-affected zone.