Toward the existence of ultrafast diffusion paths in Cu with a gradient microstructure: Room temperature diffusion of Ni
Toward the existence of ultrafast diffusion paths in Cu with a gradient microstructure: Room temperature diffusion of Ni
复制标题
具有梯度微结构的 Cu 中超快扩散路径的存在：Ni 的室温扩散
DOI：
10.1063/1.2992628
复制
发表时间：
2008-09
影响因子：
4
通讯作者：
Wang, Z. B.
中科院分区：
文献类型：
--
作者：
Divinski, S.;Wilde, G.;Lu, K.;Wang, Z. B.
严重塑性变形 SPD 是生产纳米结构材料的一条有吸引力的途径。尽管SPD材料中的扩散行为是目前的热门话题，但仍然存在一些争议。这主要是由于两个原因：热扩散处理过程中强烈的微观结构变化以及晶格位错对界面扩散的影响。通过表面机械研磨处理 SMAT，1,2 在纯度为 99.995 wt% 的铜板上生成了具有梯度微结构的表面层。详细的微观结构表征可以在参考文献中找到。 3、晶粒尺寸首先随深度逐渐增大，从顶面约10 nm到25 m深度处约100 nm，然后在深度大于500 m处接近原始微米级。具有这种梯度结构的表面层为我们研究微观结构，特别是晶粒尺寸和界面结构对纳米晶材料中界面扩散的影响提供了独特的机会。先前的研究表明，即使在低至 383 K 的温度下，Ni 也会显着渗透到 SMAT 产生的 Cu 的纳米结构表面层中。 4 为了抑制扩散退火处理期间热致结构变化可能产生的影响，本工作在室温下研究了 SMAT Cu 中 Ni 的晶界 GB 扩散。由于处理后的样品在制备后已在室温下保存了2个月以上，因此在目前的扩散实验中预计不会发生结构松弛。通过电火花腐蚀来切割圆盘样品。将SMAT表面压在抛光的WC硬质合金板上，压缩应变约为10%，以降低表面粗糙度，并将样品直径减小1毫米，以消除压制的副作用。通过干燥一滴含有扩散剂的稀 HCl 溶液，将 63 Ni 放射性同位素沉积在五个不同样品的表面：制备好的 SMAT 样品样品 A、在 423 K 预退火 60 分钟的样品 B、厚度分别为 12.5 和 27.5 m 的去除表面层的样品 C 和 D、以及退火的粗晶样品样品 O。然后将所有样品储存在室温下。 293 1K 6.510 4 秒 18 小时。扩散渗透剖面通过连续切片技术使用精密平行磨床和带有 Al2O3 颗粒 3 m 的特殊磨料 Mylar 箔来确定。通过在每个研磨步骤后称重样品，根据质量减少来确定切片厚度。每个切片中的示踪剂浓度与其比放射性成正比，即有效计数率与去除质量的比率。 63 Ni的放射性衰变数通过液体闪烁计数器TRI-CARB 2500 TR测量。图 1 绘制了 SMAT 样品中测得的 Ni 扩散曲线，并与粗粒样品中测得的“零”曲线进行了比较。为了方便比较，样品 A、B、C 和 D 中的放射性值已重新调整。靠近表面的前几个点不包含在分析中，因为它们是
Severe plastic deformation SPD is an attractive route for producing nanostructured materials. Although the diffusion behavior in SPD materials is currently a hot topic, there are still some controversies. This is mostly due to two reasons: strong microstructural changes during the thermal diffusion treatment and the lattice dislocation effect on interface diffusion. By means of surface mechanical attrition treatment SMAT, 1,2 a surface layer with a gradient microstructure has been produced on a Cu plate of 99.995 wt % purity. The detailed microstructural characterization can be found in Ref. 3. The grain size increases first gradually with the depth, from about 10 nm at the top surface to about 100 nm at a depth of 25 m and then approaches the original micrometer level at a depth larger than 500 m. The surface layer with such a gradient structure provides us a unique opportunity to study the effect of microstructure, particularly of grain size and of interface structure, on interface diffusion in a nanocrystalline material. A previous study indicated that Ni significantly penetrates into the nanostructured surface layer of Cu produced by SMAT even at a temperature as low as 383 K. 4 To suppress a possible effect of thermally induced structure variation during the diffusion annealing treatment, grain boundary GB diffusion of Ni in SMAT Cu is studied in the present work at room temperature. Since the treated samples have been stored for more than 2 months at room temperature after their preparation, no structural relaxation is expected to occur during the present diffusion experiments. The disk samples were cut by spark erosion. The SMAT surface was pressed against a polished WC hard alloy plate with a compressive strain of about 10% to reduce the surface roughness and the samples were reduced in diameter by 1 mm in order to eliminate the side effects of pressing. The 63 Ni radioisotope was deposited by drying a droplet of dilute HCl solution containing diffusant onto the surface of five different samples: the as-prepared SMAT sample sample A, the one preannealed at 423 K for 60 min sample B, the ones with removed surface layers of 12.5 and 27.5 m in thickness samples C and D, respectively, and an annealed coarse-grained sample sample O. All the samples were then stored at room temperature 293 1K for 6.510 4 s 18 h. Diffusion penetration profiles were determined by the serial-sectioning technique using a precision parallel grinder and a special abrasive Mylar foil with Al2O3 particles 3 m. The section thickness was determined from the mass reduction by weighing the sample after each grinding step. The tracer concentration in each section is proportional to its specific radioactivity, i.e., the ratio of the effective counting rate to the removed mass. The number of radioactive decay of 63 Ni was measured by a liquidscintillation counter TRI-CARB 2500 TR. The diffusion profiles of Ni measured in the SMAT samples are plotted in Fig. 1, in comparison with the “zero” profile measured in the coarse-grained sample. The radioactivity values in samples A, B, C, and D have been rescaled for a convenient comparison. The first several points close to the surface are not included in the analysis since they are
登录
查看更多内容
影响因子：
1.4
作者：
I. Kaur.;Y. Mishin;W. Gust
通讯作者：
I. Kaur.;Y. Mishin;W. Gust
嵌入纳米孪晶束的纳米晶铜的力学性能和轧制行为
影响因子：
9.4
作者：
Lu, K.;Tao, N. R.;Zhang, Y.
通讯作者：
Zhang, Y.
影响因子：
64.8
作者：
L. Rosenhead
通讯作者：
L. Rosenhead
影响因子：
1.8
作者：
Zhenhuan Lu;Yantao Xu;Zushu Hu
通讯作者：
Zhenhuan Lu;Yantao Xu;Zushu Hu
影响因子：
9.4
作者：
Divinski, Sergiy;Ribbe, Jens;Herzig, Christian
通讯作者：
Herzig, Christian