Relationship between X-ray diffraction and unidirectional solidification at interface between diamond and brazing filler metal

Brazing single crystal diamonds by using silver-copper eutectic filler containing reactive metal: titanium has been carried out. Unidirectional solidification brazing method was tried to obtain stable brazed strength. The diamond specimen was cooled down by contact with copper cooling mass of which temperature was controlled at a room temperature, 470 K and 670 K, respectively. The brazing temperature was 1080 K. The brazing filler was solidified from diamond brazing surface and we called this method as unidirectional solidification brazing. The brazed specimen was examined in shear strength by an original apparatus. In the case of diamond (100), the average shear strength shows more than 120 MPa and maximum shear strength is 240 MPa. These specimens are stronger than that made by usual brazing method. After the strength test, interface orientation between the diamond and the brazing filler was investigated by X-ray diffractometer. In the case of brazing diamond (100), diamond (100) – TiC (111) – Ag (111) orientation can be detected. In the case of brazing diamond (111), diamond (111) – Cu (111) orientation can be detected. Misfits for those orientations were calculated. The value for TiC (111) // diamond (100) is 0.05016, on the other hand the value for TiC (111) // diamond (111) is 0.2125. The brazed interface of diamond (111) is more delicate for thermal stress than diamond (100).