Evolution of microstructure and microtexture in fcc metals during high-pressure torsion
Evolution of microstructure and microtexture in fcc metals during high-pressure torsion
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DOI：
10.1007/s10853-006-0628-0
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发表时间：
2007-03
影响因子：
4.5
通讯作者：
A. Zhilyaev;T. Mcnelley;T. Langdon
中科院分区：
文献类型：
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作者：
A. Zhilyaev;T. Mcnelley;T. Langdon
选择纯镍和工业纯铝作为面心立方材料模型，详细研究了高压扭转（HPT）加工过程中影响晶粒细化和显微组织及织构演变的实验参数。HPT后，使用显微硬度测量，透射电子显微镜和取向成像显微镜检查样品。经HPT处理后，纯Ni的晶粒尺寸约为170 nm，纯Al的晶粒尺寸约为101 μm。结果表明，均匀和等轴显微组织，可以达到整个样品的镍时，使用施加的压力至少为1.6GPa后，5整个旋转。在CP铝中，在1 GPa的施加压力下旋转2整圈后获得均匀和等轴的显微组织。在这些条件下，样品中心和周边的晶界取向差分布相似。结果表明，在高压扭转条件下，面心立方金属中形成了简单的剪切织构。在8转之后，在Al盘的周边处检测到一些晶粒生长。讨论了影响HPT加工均匀组织形成的因素。
Pure nickel and commercially pure (CP) aluminium were selected as model fcc materials for a detailed investigation of the experimental parameters influencing grain refinement and evolution of microstructure and microtexture during processing by high-pressure torsion (HPT). Samples were examined after HPT using microhardness measurements, transmission electron microscopy and orientation imaging microscopy. Processing by HPT produces a grain size of ∼170 nm in pure Ni and ∼1 μm in CP aluminium. It is shown that homogeneous and equiaxed microstructures can be attained throughout the samples of nickel when using applied pressures of at least ∼6 GPa after 5 whole revolution. In CP aluminium, a homogeneous and equiaxed microstructure was achieved after 2 whole revolutions under an applied pressure of 1 GPa. For these conditions, the distributions of grain boundary misorientations are similar in the centre and at the periphery of the samples. It is shown that simple shear texture develops in fcc metals subjected to high-pressure torsion. Some grain growth was detected at the periphery of the Al disk after 8 revolutions. The factors influencing the development of homogeneous microstructures in processing by HPT are discussed.