A study was made of the wetting of Al2O3 by molten Cu-Ti and Au-Ti alloys. It is shown that the system Cu-Ti/Al2O3 is characterized by better wetting and stronger adhesion compared with the system Au-Ti/Al2O3.
To determine the effect of crystallographic orientation in the support plate, a special technique was developed, with the aid of which it was established that, qualitatively, the (0001) plane of sapphire (the plane most closely packed with oxygen) is better wetted by Cu-Ti melts than its (10-10) plane.
A study was made of the phase compositions of the transition layers in the systems Cu~Ti/Al2O3 and Au-Ti/Al2O3, for which a special method of specimen preparation was devised. It is demonstrated that the transition layer in the system Cu-Ti/Al2O3 consists mainly of TiO, and that in the system Au-Ti/ Al2O3, of Ti2O3.
The hypothesis is advanced that a system in which a more metal-like transition layer is formed may be expected to be characterized by better wetting and stronger adhesion.