Transient liquid phase bonding of aerospace single crystal Rene-N5 superalloy
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Date
2019-08-29
Authors
Adu, James
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Abstract
Due to a major concern of susceptibility of single crystal weld to solidification cracking, transient liquid phase (TLP) bonding has been developed as an attractive alternative method for the repair of these single crystal superalloys. In this research, the effect of process parameters on the joint microstructure of TLP bonded single crystal Nickel-base superalloy, Rene-N5 using the conventional filler, Nicrobraz 150 is investigated. The bonding experiments are performed at the bonding temperatures, 1090oC to 1200oC for bonding times ranging from 1 to 50 hours. The results show a variable isothermal solidification rate constant, which can be attributable to atomic diffusion coefficient that is varying with concentration and time. Furthermore, an increase in the bonding temperature is observed to result in a decrease in isothermal solidification rate constant (slope), which is in contrast to what is expected based on a binary system. The reduction in isothermal solidification rate constant may be due to difference in phase relationship in simple Ni-B binary system compared to that in multi-component Rene-N5 alloy system. Moreover, the experimental results show that the addition of additive powder material to a conventional filler alloy powder reduces the processing time compared to the use of only conventional filler, which can enhance the effectiveness of the bonding process for commercial application.
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Keywords
transient liquid phase bonding, single crystal, rene-N5, isothermal solidified zone,eutectic