纳米晶粒精密电铸层力学性能的试验研究

采用高频窄脉宽脉冲电流、高速冲液等方法获得金属镍纳米晶粒精密电铸层。分析、研究了晶粒大小对沉积层力学性能的影响。结果表明，随着晶粒尺寸的减小，沉积层微观硬度和强度性能得到了明显提高。常温条件下，沉积层晶粒从1 000 nm细化至70 nm时，其抗拉强度可提高至1 160 Mpa，但随着沉积层晶粒进一步细化，其抗拉强度呈下降趋势，出现与传统的Hall-Patch理论相背离现象。200 ℃时，得到和常温条件下类似结果，而400 ℃时，其抗拉强度随着晶粒的细化基本保持不变。

RESEARCH ON MECHANICAL PROPERTIES OF NANOCRYSTALLINE ELECTROFORMING LAYER

During the last decade, considerable attention is paid to nanocrystalline materials for their unique mechanical, physical,and chemical properties. High frequency pulse current and strong electrolyte flushing are employed to electrodeposit nanocrystalline nickel without any additives. Moreover, the effects of the grains sizes on the mechanical properties of nanocrystalline nickel are examined. It is found that the properties of the deposited nickel such as tensile strength are improved substantially with the decrease of the grain size at room temperature. The tensile strength of nickel is improved when the grain size decreased from 1 000 nm to 70 nm, at which the maximum tensile strength of 1 160 Mpa is observed. However, with the further refinement of crystal grain, the tensile strength of nickel reduces. It indicates the deviation of tensile strength from Hall-Petch relationship for nanocrystalline nickel while the grain sizes are less than 70 nm. Unlike the tensile strength at room temperature and 200 ℃, the tensile strength of nanocrystalline nickel at 400 ℃ approximately keeps constant in the range of crystal grain from 50 nm to 1000 nm.