レーザ合金化法による工業用純チタンの表面硬化処理

Abstract

In order to improve a surface hardness of commercially pure titanium, surface alloying with laser was carried out. Pure silicon, nickel, aluminum powder and a mixture of silicon and 9 mass%WSi2 powder were used for surface alloying. These powders were spread on surfaces of titanium plates and reacted with titanium by CO2 laser beam. Laser irradiation was carried out in argon atmosphere. As a result, when the silicon powder was used, a hard silicide layer (a principal ingredient was Ti5Si3) was formed over thickness 600 μm. In the case of the nickel powder, an alloying layer was consisted of TiNi and Ti2Ni, and its highest hardness was HV600. When the aluminum powder was used, needle-like shapes of precipitates of TiAl3 were observed in aluminum-rich matrix phase. Moreover, in alloying with the powder mixture of silicon and WSi2 powder, concentration phase of tungsten that had over HV1500 hardness were observed locally.