Microstructure, texture and mechanical properties of hot rolled and annealed Ni-Fe-W and Ni-Fe-W-Co matrix alloys

Abstract

Present work describes microstructure, texture and mechanical properties of hot rolled and annealed matrix Alloys (Ni-29Fe-18W (A1), Ni-29Fe-18W-5Co (A2), Ni-29Fe-18W-10Co (A3) and Ni-10Fe-30W-16Co (A4)). These alloys exhibit single fcc γ phase in hot rolled and annealed condition. The lattice constant and hardness values of A1 and A4 are smallest and largest among all the alloys, respectively. Microstructures of all the alloys display equiaxed grains along with annealing twins. The overall grains are quite fine in alloy A4 in comparison to those of the other alloys. The overall textures of hot rolled and annealed samples of all the four alloys are weak exhibiting low to moderate values of in plane anisotropy and anisotropy index. The strength of the alloy A1 is smallest while A4 displays both highest strength and maximum ductility. The flow curves of all the alloys exhibit two slopes at low and high strain regimes, respectively and follow Ludwigson constitutive equation. The differential curves of all the alloys shows three typical stages of work hardening. Dislocation controlled strain hardening occurs in all the three stages of these alloys and slip is the predominant deformation mechanism during tensile testing.