Grain refinement and superplasticity in an aluminum alloy processed by high-pressure torsion
Grain refinement and superplasticity in an aluminum alloy processed by high-pressure torsion
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DOI：
10.1016/j.msea.2004.11.007
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发表时间：
2005-02-25
期刊：
影响因子：
6.4
通讯作者：
Langdon, TG
中科院分区：
文献类型：
--
作者：
Sakai, G;Horita, Z;Langdon, TG
采用高压扭转 (HPT) 技术对 Al-3% Mg-0.2% Sc 合金圆盘进行加工，将晶粒尺寸细化至接近 0.15 μm。处理后对圆盘的检查显示中心核心区域具有相对粗糙且不明确的微观结构。该核心区域的尺寸随着 HPT 匝数的增加而减小。测量结果表明，硬度随着施加压力的增加和/或圈数的增加而增加。此外，硬度随着距盘中心的距离的增加而增加，并且在距离大于约2-3mm时稳定。在较高的施加压力和较大的转数后，圆盘外部区域的饱和硬度值相似。该饱和硬度类似于固溶处理条件下硬度的三倍。在硬度饱和区域内，微观结构相当均匀，由大角度晶界分隔的超细晶粒组成。拉伸测试表明，HPT 后出现了高应变率超塑性，其断裂伸长率与通过等通道角挤压 (ECAP) 加工的相同合金样品中获得的伸长率相似。 (C) 2004 Elsevier B.V. 保留所有权利。
Disks of an Al-3% Mg-0.2% Sc alloy were processed by high-pressure torsion (HPT) to refine the grain size to similar to0.15 mum. Inspection of the disks after processing revealed a central core region having a relatively coarse and ill-defined microstructure. The size of this core region decreased with increasing numbers of turns in HPT. Measurements showed the hardness increased with increasing applied pressure and/or increasing numbers of turns. In addition, the hardness increased with increasing distance from the center of the disk and stabilized at distances greater than similar to2-3 mm. The values of the saturation hardness in the outer regions of the disks were similar at higher applied pressures and after larger numbers of turns. This saturation hardness was similar to3x the hardness in the solution-treated condition. Within the region of hardness saturation, the microstructure was reasonably homogeneous and consisted of ultrafine grains separated by high-angle grain boundaries. Tensile testing demonstrated the occurrence of high strain rate superplasticity after HPT with elongations to failure that were similar to those obtained in samples of the same alloy processed by equal-channel angular pressing (ECAP). (C) 2004 Elsevier B.V. All rights reserved.