Effect of aging treatment on the microstructure and properties of a novel medium-heavy NiWCoTa alloy subjected to pre-deformation

Abstract

<div lang="en" class="abs"><p class="abs_header">Abstract</p><p>In this study, a new medium-heavy alloy (MHA) of 55Ni-39 W-5Co-1Ta was designed, based on the principles of face-centered cubic structures and age-strengthening. The microstructure and properties of pre-deformed MHA after aging were systematically explored by room-temperature tensile testing, scanning electron microscopy, transmission electron microscopy and x-ray diffraction. Results show that a large number of dislocations were generated in the solid solution of the MHA by pre-deformation, and the dislocation density increased significantly with deformation. The high-density dislocations interacted with each other and formed dislocation tangles, then the dislocation cells. Moreover, pre-deformation effectively promoted the precipitation of the Ni₄W phase during the subsequent aging, and the volume fraction of the Ni₄W phase increased significantly under increased pre-deformation. Thanks to a combined effect of work-hardening and age-strengthening, the tensile and yield strengths of the pre-deformed MHA after the aging treatment increased significantly. The fracture morphology of the pre-deformed MHA after the aging treatment showed typical ductile fracture characteristics. The novel MHA has better dynamic performance, and the flow stress of the MHA was effectively improved by the aging treatment.</p></div>