Deformation and damage features of a Re/Ru-containing single crystal nickel base superalloy during creep at elevated temperature

• Main Authors: Guoqi Zhao, Sugui Tian, Shunke Zhang, Ning Tian, Lirong Liu
• Format: Article
• Language: English
• Published: Elsevier 2019-04-01
• Series: Progress in Natural Science: Materials International
• Online Access: http://www.sciencedirect.com/science/article/pii/S1002007118306026

The deformation and damage features of a 4.5%Re/3.0%Ru-containing single crystal nickel-based superalloy during the creep in the temperature range of 1040–1070 °C and stress range of 137–180 MPa was investigated by means of creep properties measurement and contrast analysis of dislocation configuration. The results showed that the alloy exhibited a better creep resistance in the range of the testing temperatures and stresses, the deformation mechanism of the alloy during steady state creep was dislocations climbing over the rafted γ′ phase. In the latter period of creep, the deformation mechanism of the alloy was dislocations shearing into the rafted γ′ phase. It is believed that the dislocations shearing into γ′ phase may cross-slip from {111} to {100} planes for forming the K-W locks to restrain the slipping and cross-slipping of dislocations on {111} plane. As the creep goes on, the alternate slipping of dislocations results in the twisted of the rafted γ′ phase to promote the initiation and propagation of cracks along the γ/γ′ interfaces up to creep fracture, which is considered to be the damage and fracture feature of alloy during creep at high temperature. : In the later stage of the creep, the deformation mechanism of alloy is dislocations shearing into the rafted γ′ phase, and the dislocations shearing into γ′ phase may cross-slip from {111} to {100} planes to form the K-W locks. Wherein, the deformation mechanism of alloy during steady state creep is dislocations climbing over the rafted γ′ phase, and the strain rate of alloy during steady state creep is expressed as: ε˙=A″(VH)=A·D·h·B3(μ·b)2(1−υ)2H3exp(−Uj+Uvk·T). Keywords: Re/Ru alloying, Single crystal nickel-based superalloy, Creep, Dislocations climbing, K-W locks