2000 Volume 18 Issue 1 Pages 133-140
The effect of bonding misfit on creep rupture properties of TLP-bonded joints of Ni-base single crystal superalloy CMSX-2 were investigated bonded using MBF-80 insert metal. The bonding misfit was defined by ‹100› twist angle (rotating angle) at bonded interface. The post-bond heat treatment consisted of the solution and sequential two-step aging treatments was carried out in the Ar (oxygen partial pressure : 6.7 mPa) or vacuum (oxygen partial pressure : 4 mPa/0.27 mPa) atmosphere prior to creep rupture testing. Creep rupture properties of joints were comparable to those of base metal within the rotating angle being up to 3° while drastically fell down with increasing the rotating angle more than 5°. The boundary energy and oxygen content at bonded interface increased with increasing the rotating angle. Creep rupture properties of joints could be improved with lowering the oxygen partial pressure during post-bond heat treatment attributed to the restraint of grain boundary oxidization of bonded interface. It was deduced that the bonding misfit which promoted the grain boundary oxidization during post-bond heat treatment caused by the increment of boundary energy at bonded interface was deteriorated the creep rupture properties of joints.
