超音速微粒轰击时间对Ni-W-Co-Ta合金组织和性能的影响

Effects of supersonic fine particle bombardment time on microstructures and properties of Ni-W-Co-Ta alloy

采用超音速微粒轰击(SFPB)技术对冷轧态Ni-W-Co-Ta合金进行表面纳米化处理,系统研究了恒定气体压力(1.0 MPa)条件下SFPB时间对冷轧态Ni-W-Co-Ta合金的表面完整性、微观组织及力学性能的影响。结果表明:SFPB处理后,新型Ni-W-Co-Ta合金表层形成一定厚度的梯度纳米结构,随着SFPB时间的延长,合金表面晶粒尺寸可细化至9.74 nm左右,相应的形变层深度、力学性能(强度、残余压应力、显微硬度)均呈现出增大趋势;当SFPB时间为120 s时,合金表面粗糙度最小的同时其力学性能指标达到峰值;SFPB时间继续增加至150 s后,合金表面出现数量众多的微裂纹,残余压应力松弛的同时相应的力学性能有所下降;SFPB处理前、后新型Ni-W-Co-Ta合金的伸长率无明显变化,断口形貌均呈现出典型的韧-脆混合型断裂特征。

The surface nanocrystallization treatment of cold-rolled Ni-W-Co-Ta alloy was carried out by supersonic fine particle bombardment(SFPB)technique.The effects of SFPB time on the surface integrity,microstructure and mechanical properties of cold-rolled Ni-WCo-Ta alloy under constant gas pressure(1.0 MPa)were systematically investigated.The results show that the gradient nanostructures with certain thickness is formed on the surface layer of the novel Ni-W-Co-Ta alloy after SFPB treatment.With the extension of SFPB time,the surface grain size of the alloy can be refined to around 9.74 nm,and the corresponding deformation layer depth and mechanical properties(strength,residual compressive stress and microhardness)show an increasing trend.The surface roughness is the minimum while the mechanical properties reach the peak values when the SFPB time is 120 s.When the SFPB time reaches 150 s,the numerous micro-cracks are observed on the surface of the alloy and the residual compressive stress is relaxed while the corresponding mechanical properties are decreased.The elongation of the novel Ni-W-Co-Ta alloy does not change significantly before and after SFPB treatment,and the fracture morphologies show typical mixed tough-brittle fracture characteristics.