(1. 福州大學 材料科學與工程學院，福州 350108；
2. 福建工程學院 材料科學與工程系，福州 350108)
摘 要: 采用脈沖電沉積技術制備鈷含量在2.4%~59.3%范圍內的鎳鈷合金。利用XRD與TEM技術對納米晶鎳鈷合金的組織結構進行表征。結果表明：所有成分的納米晶鎳鈷合金均為面心立方結構的單相固溶體，平均晶粒尺寸為11~24 nm，且平均晶粒尺寸隨鈷含量的增加而減小，鎳鈷合金鍍態(tài)下TEM組織中觀察到的晶粒尺寸與XRD測量結果一致；納米晶鎳鈷合金抗拉強度為1 300~1 650 MPa，斷裂伸長率為10.5%~14.5%，鎳鈷合金的抗拉強度與斷裂伸長率均隨鈷含量的增加而提高；隨著鈷含量的不斷增加，鎳鈷合金在單向拉伸過程中的應力誘發(fā)晶粒長大被逐漸抑制，提高加工硬化率，塑性失穩(wěn)被延遲，從而提高塑性。
關鍵字: 鎳鈷合金；納米晶；力學性能；晶粒長大；變形機制
（1. College of Materials Science and Engineering, Fuzhou University, Fuzhou 350108, China;
2. Department of Materials Science and Engineering, College of Fujian Engineering, Fuzhou 350108, China）
Abstract:Ni-Co alloys with Co content varying from 2.4% to 59.3% were prepared by pulse electrodeposition nanocrystalline. The microstructures of the nanocrystalline Ni-Co alloys were characterized by XRD and TEM. The analysis of XRD indicates that nanocrystalline Ni-Co alloys are all face-centered cubic structure, single-phase solid solution with an average grain size in the range of 11−24 nm, and the average grain size decreases with increasing Co content. The grain size observed in the TEM structures of as-deposited Ni-Co alloys is consistent with that measured by XRD. For nanocrystalline Ni-Co alloys, the ultimate tension strength is in the range of 1 300−1 650 MPa and the elongation to failure is in the range of 10.5%−14.5%. Both the ultimate tension strength and the elongation to failure increase with increasing Co content. With increasing Co content, the grain growth in the process of tension deformation is gradually suppressed leading to improved work hardening rate and delayed plasticity instability, which aids to obtain enhanced ductility.
Key words: Ni-Co alloy; nanocrystalline; mechanical property; grain growth; deformation mechanism
