Abstract
The applicability of built-up repairing by isothermal solidification to Ni-base single crystal superalloy CMSX-4 was investigated using Ni-Cr-B filler metals. Base metal dissolution and isothermal solidification behaviors were examined under various heat treatment conditions. Microstructure of the repaired region could be classified into eutectic zone, normally solidified zone, isothermally solidified zone, precipitated zone in the base metal and substrate. Isothermally solidified zone and precipitated zone in the base metal were found to possess the identical crystal orientation with the base metal one. The dissolution width of base metal and the isothermal solidification width increased with repairing temperature and holding time. The single-crystallization could be achieved in the isothermally solidified zone of the repaired region. The built-up repairing up to 38μm in width could be made at the repairing condition of 1448K×176.4ks by using a Ni-Cr-B filler metal.
