Segregation of niobium in laser cladding Inconel 718 superalloy
(Shanghai Key Laboratory of Materials Laser Processing and Modification,
Shanghai Jiao Tong University, Shanghai 200240, China)
Shanghai Jiao Tong University, Shanghai 200240, China)
Abstract: Inconel 718 superalloy is widely used in the aerospace and turbine industry. Segregation of niobium appears in the laser cladding Inconel 718 superalloy and consequently influences the phase transformation during the rapid solidification. In order to control the microstructure and improve the mechanical properties of the deposited coating, the the influence of solidification conditions on the segregation of niobium and the resultant formation of Nb-rich Laves phase was studied using the microstructure observation and EDS analysis. The results show that the cooling rate has considerable influence on the microstructure of the deposited coating. High cooling rate is beneficial for suppressing the segregation of Nb and reducing the formation of Laves phase, which is believed to be detrimental to the performance of the Inconel 718 alloy.
Key words: Inconel 718 superalloy; segregation of niobium; laser cladding; cooling rate