Effect of pinning by an orientation gradient on the thermal stability of ultrafine grained Ni produced by equal channel angular pressing
Effect of pinning by an orientation gradient on the thermal stability of ultrafine grained Ni produced by equal channel angular pressing
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DOI：
10.1063/1.4867416
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发表时间：
2014-03-21
影响因子：
3.2
通讯作者：
Wilde, Gerhard
中科院分区：
文献类型：
--
作者：
Divinski, Sergiy V.;Reglitz, Gerrit;Wilde, Gerhard
研究了热退火对纯度为99.6 wt. %的等径角挤压严重变形镍的微观组织演变的影响。超细晶组织表现为大量变形带，平均晶粒尺寸约为250 nm。高温退火诱导非均匀再结晶和晶粒长大。尽管周围区域晶粒生长明显，但仍有一些小晶粒继续存在再结晶现象。这种稳定性受到特定的微观结构元素的影响，这些微观结构元素含有沿能带方向的旋转缺陷，这些旋转缺陷的取向梯度约为垂直于边界高角界面。取向梯度的钉住阻止了边界界面的运动，从而阻止了基体再结晶对晶粒的消耗。
The effect of thermal annealing on the microstructure evolution in nickel of 99.6 wt. % purity, severely deformed by Equal Channel Angular Pressing using the route, was investigated. The ultrafine grained microstructure was shown to be characterized by numerous deformation bands with an average grain size of about 250 nm. High-temperature annealing induces heterogeneous recrystallization and grain growth. Though, some small grains are found to persist recrystallization in spite of pronounced grain growth in surrounding regions. This stability is suggested to be affected by specific microstructure elements containing rotational defects with a misorientation gradient of about along the band direction and thus perpendicular to the bounding high-angle interfaces. Pinning by orientation gradient prohibits motion of bounding interfaces and thus consumption of the grain by recrystallizing matrix.