Authors: Y Tian R Gauvin M Brochu
Publish Date: 2016/04/13
Volume: 47, Issue: 7, Pages: 3771-3780
Abstract
Laser powder deposition was performed on a substrate of Inconel 738 using blended powders of Mar M247 and Amdry DF3 with a ratio of 41 for repairing purposes In the asdeposited condition continuous secondary phases composed of γNi3B eutectics and discrete Cr WB borides were observed in interdendritic regions and timedependent nucleation simulation results confirmed that Cr WB was the primary secondary phase formed during rapid solidification Supersaturated solid solution of B was detected in the γ solid solution dendritic cores The Kurz–Giovanola–Trivedi model was performed to predict the interfacial morphology and correlate the solidification front velocity SFV with dendrite tip radius It was observed from highresolution scanning electron microscopy that the dendrite tip radius of the upper region was in the range of 15 to 30 nm which yielded a SFV of approx 30 cm/s The continuous growth model for solute trapping behavior developed by Aziz and Kaplan was used to determine that the effective partition coefficient of B was approximately 0025 Finally the feasibility of the modeling results were rationalized with the Clyne–Kurz segregation simulation of B where Clyne–Kurz prediction using a partition coefficient of 0025 was in good agreement with the electron probe microanalysis resultsThe authors would like to acknowledge the support from Liburdi Turbine Service particularly Dr Alexandre Gontcharov and Dr Paul Lowden for sample preparation and technical support The authors would also like to acknowledge the McGill University Doctoral Award MEDA and NSERC for financial support Finally the authors would like to thank Mr Nicolas Brodusch for technical assistance and Dr Manas Paliwal for fruitful discussions
Keywords: