A Novel Ni-42W-10Co-1Mo Medium–Heavy Alloy with Excellent Static/Dynamic Properties

Abstract

A novel Ni-42W-10Co-1Mo (wt%) medium-heavy alloy (MHA) with excellent static/dynamic properties is designed and further optimized via heat treatment. The Ni-42W-10Co-1Mo alloy is melted via vacuum induction melting (VIM)+vacuum arc remelting (VAR) and then forged into a billet. The forged microstructure is equiaxed grains, and the μ phase is arranged in a strip, forming a band structure. The grain size increases as the solution temperature increases from 1100 to 1250 °C, whereas the grain size in the precipitated phase region is relatively small because of the pinning effect. The Ni-42W-10Co-1Mo alloy shows a balanced strength (yield strength of 530 MPa) and ductility (tensile strain of 55%) after solution treatment at 1200 °C. Moreover, the dynamic property of Ni-42W-10Co-1Mo MHA is excellent, which exhibits a positive strain rate effect at strain rates ranging from 2000 to 5000 s⁻¹. The flow stress is decreased after solution treatment, while the impact absorption energy is enhanced. The adiabatic shear band under a high strain rate is not observed under all conditions, indicating excellent impact resistance performance. The dislocation movement and twins are the main deformation mechanisms under a high strain rate. Moreover, the heterogeneous structure plays a positive effect on static and dynamic mechanical properties.