【摘要】 系统研究超音速微粒轰击(SFPB)诱导梯度纳米结构对Ni-W-Co-Ta高密度合金表面完整性、显微组织演变及力学性能的影响。结果表明：SFPB处理能在Ni-W-Co-Ta MHA表层形成梯度纳米结构。当气体压力为1.0MPa、冲击时间为60s时，合金的极限抗拉强度和屈服强度分别达到最大值1236MPa和758MPa，相比固溶态合金的提高了22.5%和38.8%，伸长率(46.3%)与固溶态合金的接近，此时，合金具有最佳的强度和塑性匹配。然而，当气体压力过大或冲击时间过长时，试样表面出现微裂纹，在残余应力发生一定程度松弛的同时强度下降。形变层深度和表面显微硬度随着冲击时间的延长及气体压力的增大逐渐增大，在1.0MPa及120s时分别达到最大值29μm和HV 451，表层晶粒则细化至最小值11.67 nm。经SFPB处理后Ni-W-Co-Ta MHA的伸长率变化不大，断裂方式由处理前的韧性断裂转变为处理后的韧、脆混合断裂。更多还原

【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.更多还原