Low-temperature tensile properties of Cu-Fe laminated sheets with various number of layers
Low-temperature tensile properties of Cu-Fe laminated sheets with various number of layers
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DOI：
10.1016/j.msea.2021.141066
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发表时间：
2021-03
期刊：
影响因子：
6.4
通讯作者：
N. Koga;S. Tomono;O. Umezawa
中科院分区：
文献类型：
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作者：
N. Koga;S. Tomono;O. Umezawa
采用累积叠轧工艺制备了不同层数的Cu-Fe叠层板，研究了叠层层数对Cu-Fe叠层板组织和低温拉伸性能的影响。讨论了铜铁双相材料具有优异低温拉伸性能的原因。用于制造Cu-Fe叠层片材的纯铜和Fe片材的拉伸性能表现出在面心立方（fcc）和体心立方（bcc）金属的情况下所见的典型温度依赖性。层压片材的层结构保持到层数为100，但是在1000层片材的情况下破裂，其显示出网络状结构。的片材的导电性是独立的层数和显着高于Cu-Fe合金，表明铁既没有溶解，也没有沉淀在层压片材的Cu层。在50层、100层和1000层片材的情况下，强度随着温度的降低而增加，而其伸长率保持不变。直到层数为7层时才观察到小面断裂面，而在由50层以上组成的片材的情况下，在两层的断裂面上观察到微小的凹痕，表明发生了延性断裂。当在77 K下进行拉伸变形时，在50层的叠层板中，Fe层的应变集中位置周围的Cu层中的应变高。Fe层中的应变集中可能被周围的软Cu层所调节，从而抑制Fe层中解理裂纹的形核。这应该是Cu-Fe层状片材在低温下表现出优异伸长率的原因之一。因此，Cu-Fe层状结构对fcc和bcc双相材料优异的低温拉伸性能起着重要作用。
The Cu-Fe laminated sheets with various number of layers were produced by the accumulative roll bonding process, and the effects of the number of layers on the microstructure and low-temperature tensile properties of the sheets were elucidated. Then the reason for the excellent low-temperature tensile properties in dual-phase materials of Cu and Fe was discussed. The tensile properties of the pure Cu and Fe sheets used for fabricating the Cu-Fe laminated sheets exhibited the typical temperature dependence seen in the case of face-centered cubic (fcc) and body-centered cubic (bcc) metals. The layered structure of the laminated sheets was maintained till the number of layers was 100 but broke in the case of the 1000-layer sheet, which showed a network-like structure. The electrical conductivity of the sheets was independent of the number of layers and significantly higher than that of a Cu-Fe alloy, indicating that Fe had neither dissolved nor precipitated in the Cu layers of the laminated sheets. In the case of the 50-, 100- and 1000-layer sheet, the strength increased with lowering the temperature, while its elongation remained constant. A facet fracture surface was observed until the number of layers was 7, while in the case of the sheets consisting of more than 50-layers, fine dimples were observed on the fracture surfaces of both layers, indicating that ductile fracturing occurred. The strain in the Cu layers around the strain concentration sites of the Fe layers was high in the 50-layer laminated sheet when it was subjected to tensile deformation at 77 K. The strain concentration in the Fe layers might be accommodated by the surrounding soft Cu layers, resulting in the suppression of the nucleation of cleavage cracks in the Fe layers. This should be one of the reasons that the Cu-Fe layered sheets exhibited excellent elongation at low temperatures. Thus, the Cu-Fe layered structure take an important role for the excellent low-temperature tensile properties in the fcc and bcc dual-phase materials.