Info

Title:

The influence of carbon contents on the microstructure and tensile preperties of a Ni-base single crystal superalloy

Author(s):

Tao Yan; Li Yongmei; Tan Zihao; Cao Liang; Wang Xinguang

1.School of Mechanical Engineering，Liaoning Petrochemical University，Fushun 113001，China 2. Chinese Academy of Science，Institute of Metal and Research，Shenyang 110006，China

Keywords:

Ni-based single-crystalsuperalloy; turbine blades; tensile strength; carbides; directional solidification

CLC:

PACS:

-

DOI:

-

DocumentCode:

Abstract:

The effect of carbon content on the microstructure and tensile properties, as well as the deformation behavior of a low-cost second-generation Ni-based single-crystal superalloy, was investigated. The results showed that the area fraction of eutectic microstructure in the interdendritic region decreased with the increase in carbon content, while the content of MC-type carbides increased correspondingly. After standard heat treatment, there was no significant difference in γ + γ′ microstructure for alloys with different carbon contents. For tensile properties, the increase of carbon content led to a decrease in tensile strength and plasticity at both 800 °C and 1100 °C. The granular M6C-type carbides coherently precipitation from the γ′ phase during the tensile deformation, which helps to hinder superdislocation cutting into the γ′ phase, but the Ta- and W-rich MC carbides located in the dendrites will consume a large number of refractory elements, which substantially weaken the solid solution strengthening effect of γ matrix, resulting in a reduction of tensile strength. The interdendritic skeleton-like MC carbides will promote the cleavage fracture along the carbides, and accelerate the micro-crack initiation and macro-crack extension, which are considered as the main reason for the decrease in the alloy’s plasticity at 800℃and 1100℃ respectively.