Effect of γ′ Precipitation on Lamellar M23C6 Carbide Precipitation in GH4145 Alloy
HUA Peitao 1 , CHEN Sibo 2 , ZHANG Weihong 1 , YAO Xiaoyu 1 , SUN Wenru 1
( 1. Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China; 2. AECC Shenyang Liming Aero-Engine Co., Ltd., Shenyang 110000, China )
Abstract：The lamellar M23C6 phase is a typical harmful microstructure formed in the superalloys including GH4145. The mechanism for the precipitation of the lamellar structure has been investigated extensively, the conditions for the precipitation of the lamellar structure of the M23C6 carbide, however, remains unclear till now. By analyzing the precipitation of γ′ and M23C6 phases during the cooling after the 980℃ solution and the subsequent 730℃ aging, it was found that the lamellar M23C6 precipitation was directly governed by the γ′ precipitation. After the 980℃ solution, the γ′ precipitation could be prohibited thoroughly when the cooling rate is higher than 22℃/s. During the subsequent 730℃ aging after the 980℃ solution, the M23C6 carbide precipitated as isolated particles when the γ′ phase pre-precipitated in the matrix, because the γ′ phase would inhibit the directional growth of the carbide. While the M23C6 carbide might grow into lamellar form with the γ′ phase by the eutectoid reaction of (M23C6+γ′) when there was no the γ′ precipitates in the matrix before the aging. The coprecipitation of M23C6 and γ′ is the necessary conditions for the formation of the lamellar M23C6 carbide.
2020, 
