[Studies on Ni-Ta alloys. (Part 2) Age-hardening and metal-to-ceramic bonding (author's transl)].

Age-hardening and metal-to-ceramic bonding were studied on Ni-Ta alloy for dental application. In the first experiment, it was shown the precipitation-hardening was recognized in Ni-33 wt% Ta, Ni-34 wt% Ta except for Ni-30 wt% Ta. The precipitates were of a Widmamstätten type structure and appeared to be a intermetallic compound, namely Ni3Ta, from the results of X-ray diffraction (debyesherrer) despite of the close proximity of the diffraction patterns of Ni and Ni2Ta. In the second experiment, it was shown that the bonding strength was 176 kg/cm2 for Ni-30 wt% Ta-ceramic system, compared with that of 222 kg/cm2 of Wiron S-ceramic system. The oxide layer was as wide as 3 approximately 5 micron at the Ni-30 wt% Ta-ceramic interface, in which high concentrations of Ni, Ta, and low concentrations of Al, Si were observed. The coefficient of thermal expansion, which was larger than that of porcelain, was 17.4 x 10(-6)/degrees C for Ni-30 wt% Ta.