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采用直流电沉积工艺,制备了平均晶粒尺寸为56nm的致密纳米晶铜.室温下进行单向拉伸实验,发现纳米晶铜的强度和韧性均随应变速率的升高而增大,特别是韧性的速率敏感十分显著.应变速率由1.04×10-5s-1升至1.04s-1时,断裂应变由23.2%增至39.4%,同时抗拉强度由309MPa增至451MPa.这一现象可归因于两个方面:首先,纳米晶铜的应变硬化行为随应变速率的升高而增大,从而使其均匀变形阶段的应变增加;其次,高应变速率下纳米晶铜颈缩时发生晶粒转动,这有助于其失稳阶段的应变增加.
Dense nanocrystalline copper with an average grain size of 56nm was prepared by direct current deposition.The uniaxial tensile tests at room temperature showed that the strength and toughness of nanocrystalline copper increased with the increase of strain rate, especially the toughness The strain rate increased from 23.2% to 39.4% when the strain rate increased from 1.04 × 10-5s-1 to 1.04s-1, and the tensile strength increased from 309MPa to 451MPa. In two aspects: firstly, the strain hardening behavior of nanocrystalline copper increases with the increase of strain rate, so that the strain of nanocrystalline copper increases at the stage of uniform deformation; secondly, the grain rotation occurs during the shrinkage of nanocrystalline copper at high strain rate , Which helps to increase the strain on its destabilization phase.