中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 35 No. 6 June 2025 |
（1. School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang 471023, China;
2. Provincial and Ministerial Co-construction of Collaborative Innovation Center for Non-ferrous Metal New Materials and Advanced Processing Technology, Luoyang 471023, China;
3. Luoyang Optoelectronic Technology Development Center, Luoyang 471003, China;
4. Research Institute of Special Steels, Central Iron and Steel Research Institute Company Limited, Beijing 100081, China;
5. CITIC Heavy Industries Co., Ltd., Luoyang 471039, China;
6. Nano and Molecular Systems Research Unit, University of Oulu, Oulu, FIN-90014, Finland）
Abstract:The effects of gradient nanostructures induced by supersonic fine particle bombardment (SFPB) on the surface integrity, microstructural evolution, and mechanical properties of a Ni-W-Co-Ta medium-heavy alloy (MHA) were systematically investigated. The results show that gradient nanostructures are formed on the surface of Ni-W-Co-Ta MHA after SFPB treatment. At a gas pressure of 1.0 MPa and an impact time of 60 s, the ultimate tensile strength and yield strength of the alloy reached the maximum values of 1236 MPa and 758 MPa, respectively, which are 22.5% and 38.8% higher than those of the solid solution treated alloy, and the elongation (46.3%) is close to that of the solid solution treated alloy, achieving the optimal strength–ductility synergy. However, microcracks appear on the surface with excessive gas pressure and impact time, generating the relaxed residual stress and decreased strength. With the increase of the impact time and gas pressure, the depth of the deformation layer and the surface microhardness gradually increase, reaching the maximum values (29 μm and HV 451) at 1.0 MPa and 120 s. The surface grain size is refined to a minimum of 11.67 nm. Notably, SFPB treatment has no obvious effect on elongation, and the fracture mode changes from the ductile fracture before treatment to ductile–brittle mixed fracture after treatment.
Key words: supersonic fine particle bombardment; gradient nanostructure; Ni-W-Co-Ta medium-heavy alloy; microstructure; mechanical properties
