Forming and growing mechanisms of homogenization-solution pores in a single crystal superalloy

作     者：Xiao-Dai Yue Jia-Rong Li Xiao-Guang Wang Zhen-Xue Shi 

作者机构：Science and Technology on Advanced High Temperature Structural Materials LaboratoryBeijing Institute of Aeronautical Materials 

出 版 物：《Rare Metals》 (稀有金属（英文版）)

年 卷 期：2018年第37卷第5期

页      面：399-406页

核心收录：

学科分类：08[工学] 080502[工学-材料学] 0805[工学-材料科学与工程（可授工学、理学学位）] 

基　　金：financially supported by the Foundation of Beijing Institute of Aeronautical Materials (No. 150109) 

主　　题：Single crystal superalloy Pore Homogenization Solution Heat treatment Incipient melting 

摘      要：The forming and growing mechanisms of homogenization-solution pores in a single crystal superalloy were investigated. The microstructures were observed with optical microscope （OM） and field emission microscope （FEM） after homogenization-solution heat treated at 1328℃ and 1350 ℃ for 2 h, 6 h and 9 h. Results indicate that when heat treated at 1328 ℃, pores appear at the interface of eutectic and matrix at first and then leave in the matrix with the shrink of eutectic. When heat treated at 1350 ℃, incipient melting happens at first, and some of them have a pore in the center. After that, with the homogenization-solution process, incipient melting microstructure fades away gradually. By analyzing the results with thermodynamics and kinetics methods, it is concluded that some pores nucleate during directional solidification and then become larger and visible during homogenization-solution heat treatments; some pores are generated by incipient melting, yet such pores are difficult to be distinguished from other pores; imbalanced elements cross-diffusion induces to the forming and growing of pores too, and such imbalanced diffusion also plays an important part on the growth of all preexisting pores.