Effects of loading rate and peak load on nanoindentation creep behavior of DD407 Ni-base single crystal superalloy
(1. Department of Engineering Mechanics, School of Civil Engineering, Wuhan University, Wuhan 430072, China;
2. School of Civil Engineering and Architecture, Wuhan Institute of Technology, Wuhan 430074, China;
3. State Key Laboratory of Water Resources & Hydropower Engineering Science, Wuhan University, Wuhan 430072, China)
2. School of Civil Engineering and Architecture, Wuhan Institute of Technology, Wuhan 430074, China;
3. State Key Laboratory of Water Resources & Hydropower Engineering Science, Wuhan University, Wuhan 430072, China)
Abstract: Nanoindentation experiments were conducted under loading rates of 500–6000 μN/s and applied peak loads of 4000-12000 μN to measure the creep behavior of DD407 Ni-base single crystal superalloy at room temperature. Experimental results demonstrated that DD407 Ni-base single crystal superalloy had a good creep resistance, but its creep properties were sensitive to the loading rate and peak load. The fitting creep parameters significantly increased with increasing loading rate and peak load based on the Findley’s model, and the corresponding creep mechanism was governed by dislocation based on the calculation of creep stress exponent. During nanoindentation creep tests, it was found that the hardness and reduced modulus decreased with increasing the loading rate and peak load, and through a dimensionless analysis, it was also noted that the effect of the dimensionless loading rate was stronger than that of dimensionless peak load on the creep properties.
Key words: DD407 Ni-base single crystal superalloy; nanoindentation; Findley’s model; creep; stress exponent