镍基单晶合金组织演化及对晶格错配度的影响

Influence of microstructure evolution on lattice misfit of a single crystal nickel based superalloy

通过对不同状态单晶镍基合金进行组织形貌的观察和X-ray衍射分析,研究了组织演化对合金中γ′、γ两相晶格常数和错配度的影响．结果表明:铸态单晶合金不同区域中γ′相的形貌和尺寸有较大的差别,致使γ、γ′两相的晶格常数及错配度较大;将合金高温固溶处理和空冷后,均匀且细小的立方γ′相自γ基体中析出,使合金中γ′、γ两相的晶格常数及错配度减小;经完全热处理后,立方γ′相均匀长大,并保持共格界面,使γ′、γ两相的晶格常数及错配度略有增加．合金经有或无应力时效后,γ′相发生定向粗化,并在两相之间出现界面位错,使合金中γ′、γ两相的晶格常数及错配度增加．其中,由于外加应力的作用,致使塑性较好的γ相晶格常数增加的幅度大于γ′相．

The influences of microstructure evolution of a single crystal nickel based surperalloy with different states on the lattice parameter and misfit was investigated by means of microstructure observation and XRD diffraction analysis. The results show that the fine and disperse cubic γ＇ phase is precipitated from the γ matrix after solution treated, which keeps the small values of the lattice parameter and misfit of γ＇/γ phases. The cubic γ＇ phase grows up in the further under the condition of full heat treatment, so that increases slightly the parameter and misfit of γ＇/γ phases. The directional coarsen of γ＇ phase occurs, which promotes the increase of the parameter and misfit of γ＇/γ phases during stress and unstress aged treated. The extent of γ phase lattice parameter increased is much more than the γ＇ phase due to the role of the applied tensile stress.