Abstract

Medium heavy alloy (MHA) with intermediate (50–75 wt%) W contents has been considered to be a promising alternative to costly tungsten (≥ 90 wt%) heavy alloy. However, superior mechanical property is always a necessity to compensate for the reduced W. Herein, a thermomechanical processing approach, including casting, solid solution treatment and plastic deformation procedures proposed to prepare high strength Ni-W-Co-Ta MHA efficiently. Specifically, the critical plastic deformation method is orthogonal rolling where the rolled alloy was rotated by 90° about the rolling direction in order to mitigate the anisotropic drawbacks by conventional unidirectional and cross rolling. The influence of processing parameters, such as rolling method and accumulated strain, on the microstructure evolution and mechanical property characteristics were explored. It was found that Ni-W-Co-Ta MHA prepared by orthogonal rolling exhibited 100 MPa greater enhancement in strengths than that by unidirectional rolled one. Surprisingly, the elongation at tensile failure achieved 13.8%, much higher than unidirectional rolled of elongation (8.7%). This excellent combination of strength and ductility was found to be due to the relatively homogeneous deformed microstructure by orthogonal rolling other than the typical fiber microstructure by unidirectional rolling. Without extra capital investment in infrastructures, it is believed that this rolling processing procedures can also be used for other alloys.