Severe plastic deformation (SPD) and nanostructured materials by machining
Severe plastic deformation (SPD) and nanostructured materials by machining
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DOI：
10.1007/s10853-006-0745-9
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发表时间：
2007-01
影响因子：
4.5
通讯作者：
S. Swaminathan;M. Ravi Shankar;B. Rao;W. Compton;S. Chandrasekar;A. King;K. Trumble
中科院分区：
文献类型：
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作者：
S. Swaminathan;M. Ravi Shankar;B. Rao;W. Compton;S. Chandrasekar;A. King;K. Trumble
通过金属和合金的平面应变 (2-D) 加工形成的切屑中可以施加 1 到 15 之间的大塑性应变。该方法已用于检查模型系统（铜及其合金、沉淀硬化铝合金、钛等高强度材料、Inconel 718 和 52100 钢以及非晶态合金）中大应变变形引起的微观结构变化。结果表明，通过改变加工参数可以产生平均晶粒尺寸在 60 nm–1 μm 范围内的材料，这反过来又会影响变形过程。此外，在其中几种材料的较高应变水平下，已经证明了从细长亚晶微观结构到以大角度晶界为主的等轴纳米晶微观结构的转变。通过改变变形条件可以容易地控制这种切换。动态再结晶已在特定的应变和温度条件下在选定的材料系统中得到证实。这项研究可以被视为在进一步理解大应变变形的微观结构细化与纳米结构材料在结构和机械应用中的实际应用之间架起了一座重要的桥梁。传统的平面应变加工已被证明是一种可行的 SPD 方法，用于检查非常大的应变变形的基本过程。
Large plastic strains between 1 and 15 can be imposed in chips formed by plane-strain (2-D) machining of metals and alloys. This approach has been used to examine microstructure changes induced by large strain deformation in model systems—copper and its alloys, precipitation-hardenable aluminum alloys, high-strength materials such as titanium, Inconel 718 and 52100 steel, and an amorphous alloy. It is shown that materials with average grain sizes in the range of 60 nm–1 μm can be created by varying the parameters of machining, which in turn affects the deformation processes. Furthermore, a switch-over from an elongated subgrain microstructure to an equi-axed nanocrystalline microstructure, with a preponderance of large-angle grain boundaries, has been demonstrated at the higher levels of strain in several of these materials. This switch-over can be readily controlled by varying the deformation conditions. Dynamic recrystallization has been demonstrated in select material systems under particular conditions of strain and temperature. This study may be seen as providing an important bridge between furthering the understanding of microstructural refinement by large strain deformation and the practical utilization of nanostructured materials in structural and mechanical applications. Conventional plane-strain machining has been shown to be a viable SPD method for examining the underlying processes of very large strain deformation.