Potential of High Compressive Ductility of Ultrafine Grained Copper Fabricated by Severe Plastic Deformation
Potential of High Compressive Ductility of Ultrafine Grained Copper Fabricated by Severe Plastic Deformation
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DOI：
10.3390/met10111503
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发表时间：
2020-11-01
期刊：
影响因子：
2.9
通讯作者：
Yalcinkaya, Tuncay
中科院分区：
文献类型：
--
作者：
Asano, Mayu;Yuasa, Motohiro;Yalcinkaya, Tuncay
强塑性变形（SPD）可以通过形成超细晶（UFG）组织来制备高强度材料。拉伸试验中UFG材料的低断裂伸长率通常被认为是材料延展性的量度，这归因于UFG结构的低应变硬化，其中位错滑移及其积累非常有限。在目前的工作中，它表明，压缩延伸性的UFG材料可以是相当的或潜在的上级退火材料，通过使用平行圆棒压缩（PRBC）的测试，其目的是施加一个适当的应力状态，优选使用剪切模式的高延展性。UFG材料的高压缩延伸率可以是非平衡晶界处的局部应变不相容性的高适应性和晶界介导的变形机制的结果，这导致对空隙形成和生长的高损伤容限。低的应变速率敏感性表明，超塑性变形的粘性本质是不参与UFG材料使用SPD的高压缩塑性。
Severe plastic deformation (SPD) can fabricate high-strength materials by forming an ultrafine grained (UFG) microstructure. Low elongation to failure of UFG materials in tensile tests, which has often been regarded as a measure of ductility of materials, has been attributed to low strain hardening of UFG structures where dislocation slip and its accumulation is very limited. In the present work, it is shown that the compressive extensibility of UFG materials can be comparable or potentially superior to that of annealed materials by using a parallel round-bar compression (PRBC) test which was designed for imposing an appropriate stress state preferable for high ductility using the shear mode. The high compressive extensibility of UFG materials can be a result of high accommodation of local strain incompatibility at non-equilibrium grain boundaries and a grain boundary-mediated deformation mechanism, which result in high damage tolerance against void formation and growth. Low strain rate sensitivity indicated that the superplastic viscous nature of deformation is not involved in the high compressive ductility of UFG materials using SPD.