Abstract

Hexagonal samples with an initial coarse-grained structure (CG) in the near-axis zone and a gradient ultrafine-grained (UFG) structure at the periphery are formed by twist extrusion (TE) of commercial-purity copper through a hexagonal twist die with a small twist-line slope. This hybrid structure of the samples provides conditions for a large uniform deformation before necking (due to the CG core) and a high yield strength (due to the gradient UFG periphery). The hybrid CG–UFG structure can be formed due to the threshold nature of metal grain refinement during cyclic deformation. A simple relation is derived for estimating the CG core diameter of the sample. The structure and the texture of the samples are investigated by X‑ray diffraction and optical microscopy.

中文翻译：

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通过扭曲挤压在材料中形成渐变结构

摘要

通过将商用纯铜通过六角挤压模具的扭曲挤出（TE）形成六角形样品，该样品在近轴区域具有初始粗晶粒结构（CG），在外围具有梯度超细晶粒（UFG）结构。较小的扭曲线斜率。样品的这种混合结构为颈缩之前大均匀变形（由于CG核）和高屈服强度（由于梯度UFG外围）提供了条件。由于循环变形过程中金属晶粒细化的阈值性质，可以形成CG-UFG杂化结构。推导一个简单的关系来估计样品的CG芯直径。通过X射线衍射和光学显微镜研究了样品的结构和质地。