Diffusion of Ag and Co in ultrafine-grained α-Ti deformed by equal channel angular pressing
Diffusion of Ag and Co in ultrafine-grained α-Ti deformed by equal channel angular pressing
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DOI：
10.1063/1.3650230
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发表时间：
2011-10-15
影响因子：
3.2
通讯作者：
Wilde, Gerhard
中科院分区：
文献类型：
--
作者：
Fiebig, Jochen;Divinski, Sergiy;Wilde, Gerhard
研究了Co和Ag在粗晶和超细晶α-Ti中的晶界扩散。采用等通道转角挤压（ECAP）方法制备了超细晶Ti，并在没有明显晶粒长大的温度区间内进行了扩散测量。钴的晶界扩散被认为是1-2个数量级慢UFG钛，尽管伴随的激活焓是类似的粗晶α-钛。相比之下，银的晶界扩散发生在一个显着更高的速率在ECAP改性的UFG钛。这种行为是与特定的扩散机制的Ag和Co：而Ag扩散优先通过替代网站，扩散的Co是占主导地位的间隙跳跃。扩散测量证实了UFG Ti中存在所谓的非平衡界面，为非平衡扩散的Co提供了更高密度的陷阱，同时增强了Ag的置换扩散。(C)2011年美国物理学会。[doi：10.1063/1.3650230]
Grain boundary diffusion of Co and Ag was investigated in coarse-grained and ultrafine-grained (UFG) alpha-Ti. Ultrafine grained Ti was produced by equal channel angular pressing (ECAP) and diffusion measurements were performed in a temperature interval where no significant grain growth occurred. Grain boundary diffusion of Co was found to be 1-2 orders of magnitude slower in UFG Ti, despite the attendant activation enthalpy being similar to that in coarse-grained alpha-Ti. By contrast, grain boundary diffusion of Ag occurred at a significantly higher rate in the ECAP-modified UFG Ti. This behaviour is associated with the specific diffusion mechanisms of Ag and Co: while Ag diffuses preferentially via substitutional sites, diffusion of Co is dominated by interstitial jumps. The existence of so-called non-equilibrium interfaces in UFG Ti, providing an increased density of traps for the interstitially diffusing Co and simultaneously enhancing substitutionally diffusion of Ag, is confirmed by the diffusion measurements. (C) 2011 American Institute of Physics. [doi:10.1063/1.3650230]