(1. 東北農(nóng)業(yè)大學(xué) 工程學(xué)院，哈爾濱 150030；
2. 吉林大學(xué) 材料科學(xué)與工程學(xué)院，長春 130022)
摘 要: 采用直流電沉積方法制備晶粒尺寸為15 nm的Ni-49.2 %Co(質(zhì)量分?jǐn)?shù))和16 nm的Ni-66.7%Co(質(zhì)量分?jǐn)?shù))合金。采用XRD、TEM和MTS-810萬能材料試驗(yàn)機(jī)對(duì)其微觀結(jié)構(gòu)和力學(xué)性能進(jìn)行分析。結(jié)果表明：兩種合金分別是單相FCC結(jié)構(gòu)和FCC與HCP共存的雙相結(jié)構(gòu)。固溶強(qiáng)化和晶粒細(xì)化的作用使兩種Ni-Co合金都具有很高的抗拉強(qiáng)度；且Co元素的引入降低材料的層錯(cuò)能，提高其應(yīng)變硬化能力，使Ni-Co合金的塑性也明顯提高；Ni-49.2 %Co合金的抗拉強(qiáng)度(σb)和斷裂伸長率(δ)分別為1 650 MPa和9%，Ni-66.7%Co合金的σb和δ分別為2 200 MPa和12%。Ni-66.7%Co合金中FCC和HCP結(jié)構(gòu)相互協(xié)調(diào)，在變形過程中釋放內(nèi)應(yīng)力，使材料應(yīng)變硬化能力得以保持，所以獲得更高的強(qiáng)度和塑性。
關(guān)鍵字: 鎳鈷合金；電沉積；納米晶；雙相結(jié)構(gòu)；力學(xué)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
