(1. 东北农业大学 工程学院，哈尔滨 150030；
2. 吉林大学 材料科学与工程学院，长春 130022)
摘 要: 采用直流电沉积方法制备晶粒尺寸为15 nm的Ni-49.2 %Co(质量分数)和16 nm的Ni-66.7%Co(质量分数)合金。采用XRD、TEM和MTS-810万能材料试验机对其微观结构和力学性能进行分析。结果表明：两种合金分别是单相FCC结构和FCC与HCP共存的双相结构。固溶强化和晶粒细化的作用使两种Ni-Co合金都具有很高的抗拉强度；且Co元素的引入降低材料的层错能，提高其应变硬化能力，使Ni-Co合金的塑性也明显提高；Ni-49.2 %Co合金的抗拉强度(σb)和断裂伸长率(δ)分别为1 650 MPa和9%，Ni-66.7%Co合金的σb和δ分别为2 200 MPa和12%。Ni-66.7%Co合金中FCC和HCP结构相互协调，在变形过程中释放内应力，使材料应变硬化能力得以保持，所以获得更高的强度和塑性。
关键字: 镍钴合金；电沉积；纳米晶；双相结构；力学性能
（1. College of Engineering, Northeast Agricultural University, Harbin 150030, China;
2. College of Materials Science and Engineering, Jilin University, Changchun 130022, China）
Abstract:Nanocrystalline Ni-49.2%Co (mass fraction) and Ni-66.7%Co (mass fraction) alloys were synthesized by direct current electrodeposition with grain sizes of 15 and 16 nm, respectively. The Ni-49.2%Co alloy shows single FCC phase, and Ni-66.7%Co alloy possesses a mixture structure of FCC and HCP phase. The microstructure and mechanical properties of were studied by XRD, TEM and tensile tests carried out on MTS-810 tester. The high strength of Ni-Co alloys is attributed to the grain refinement and solid-solution hardening effects. The addition of Co element decreases the stacking fault energy of nanocrystalline Ni alloy, which improves the strain hardening ability and thus enhances the ductility. The ultimate tensile strength (σb) and elongation to failure (δ) of Ni-49.2%Co alloy are 1 650 MPa and 9%, respectively. Correspondingly, the σb and δ of Ni-66.7%Co alloy are 2 200 MPa and 12%, respectively. Cooperative deformation of the two phases releases the stress during deformation effectively, which contributes to the sustained high strain hardening and ductility of the Ni-66.7%Co alloy.
Key words: Ni-Co alloy; electrodeposition; nanocrystalline; dual-phase microstructure; mechanical property
