Stress rupture properties and deformation mechanisms of Nimonic 105 alloy at intermediate temperature

Publication date: Available online 11 February 2020Source: Materials Science and Engineering: AAuthor(s): Tao Peng, Bin Yang, Gang Yang, Lu Wang, Zhihua GongAbstractThe microstructural evolution, stress rupture properties and deformation mechanisms of Nimonic 105 alloy at 800 °C within stress range of 350-200 MPa were investigated through a combination of scanning electron microscopy (SEM), transmission electron microscopy (TEM) and stress rupture tests. It is found that the rupture time of the alloy increased from 201 to 9591 h as the stress decreased from 350 to 200 MPa at 800 °C. During the stress rupture tests, evident coarsening of γ′ precipitate and M23C6 carbide occurred while the morphology and distribution of MC carbide had no significant change. The growth of γ′ precipitates follows the LSW theory. TEM observations showed that the deformation mechanisms of the alloy were Orowan bypassing, strongly coupled dislocations (SCD) shearing and microtwinning during the stress rupture tests at 350-200 MPa/800 °C, and Orowan bypassing was the dominant deformation mechanism. In addition, the fracture mechanism of the alloy was also studied. The results revealed that cavities nucleated mainly at the interface of carbides (M23C6 and MC) on the grain boundary (GB). Growth and coalescence of these cavities resulted into the formation of cracks, and fracture of the alloy occurred by the cracks propagation along the GBs.

Source: Materials Science and Engineering: A - February 12, 2020 Category: Materials Science Source Type: research