Room temperature creep behavior of a single crystal nickel-based alloys

Abstract

The deformation characteristics of a single-crystal nickel-based alloy containing Re during creep at room temperature were studied by means of creep property tests, microstructure observations and contrast analysis of the dislocation configuration. The results show that during the deformation of the alloy at room temperature, the original cubic γ′ phase transforms into a rhombus shape along the direction of maximum shearing stress, and its deformation feature is that the dislocation slips in the matrix and shears the γ′ phase. The <110> superdislocation shear into the γ′ phase can cross slip from the {111} plane to the {100} plane, forming a K-W lock, and can also be decomposed at the {111} plane. The dislocation configurations of (1/2)<110> partial dislocation plus antiphase boundary (APB) and (1/3)<112> partial dislocation plus SISF can effectively inhibit the slip and cross-slip of the dislocation and improve the deformation resistance of the alloy. At the later stage of creep, under the action of shear stress, the initial slip system is activated first to distort the γ and γ′ phases, and then the secondary slip system is activated and shears the primary slip system, resulting in a large stress concentration at the delivery point and the initiation of cracks in this area. With the alternating activation of the primary slip system and secondary slip system during creep, the initiation and expansion of cracks continue. Damage and fracture mechanisms occur in alloys during room temperature creep.