Mechanical response and microstructural evolution of Ni-27 W alloys during uniaxial tension

Abstract

In face-centered cubic alloys, an outstanding combination of strength and ductility can be achieved through reducing the stacking fault energy. In this paper, the mechanical response and microstructural evolution of Ni-27 W alloys (with 27 wt% W) are studied. The Ni-27 W solid solution alloys have a face-centered cubic structure. A stacking fault energy of ~67 mJ/m2 is evaluated by the thermodynamic method. The yield stress, ultimate tensile strength, and percentage elongation to fracture of the Ni-27 W alloys are 415 MPa, 1285 MPa and 42%, respectively, which shows a high strain hardening capacity. The deformation mechanism of the Ni-27 W alloys has been investigated by means of transmission electron microscopy, electron backscatter diffraction, and high-energy x-ray diffraction at the deformation stages with true strains of 0.02, 0.1, 0.2, and 0.3. A fiber texture with <111> and <001> parallel to the tensile direction is gradually formed under uniaxial deformation. Planar dislocation structure is clearly observed, the spacing of which gets thinner as increasing the deformation strain. Planar slip dominates the plastic deformation, which results in a high strain hardening capacity.