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Tensile deformation behavior of ultrafine-grained (UFG) copper processed by accumulative roll-bonding (ARB) was studied under different strain rates at room temperature. It was found that the UFG copper under the strain rate of 10[Formula: see text] s[Formula: see text] led to a higher strength (higher flow stress level), flow stability (higher stress hardening rate) and fracture elongation. In the fracture surface of the sample appeared a large number of cleavage steps under the strain rate of 10[Formula: see text] s[Formula: see text], indicating a typical brittle fracture mode. When the strain rate is 10[Formula: see text] or 10[Formula: see text] s[Formula: see text], a great amount of dimples with few cleavage steps were observed, showing a transition from brittle to plastic deformation with increasing strain rate.

Some mechanisms of creep, especially those involving dislocations for many crystalline materials, can be verified by direct microstructural examination. However, metallic glass thin films (MGTFs) are disordered materials lacking the long-range order of crystals. Even today, the creep mechanisms for amorphous alloys are far from being fully understood. The physical factors governing localization and instability during creep deformation are still elusive. In this work, Ni60Nb40 alloys with high kinetic stability were prepared by magnetron sputtering at different substrate temperatures to obtain MGTFs with different internal states. We report a close correlation between the internal states and the creep resistance of the MGTFs and reveal that altering the substrate temperature during magnetron sputtering can induce changes in the surface morphologies, plastic deformation resistance, and creep resistance of Ni60Nb40 MGTFs. The creep deformation mechanism is interpreted based on the shear transformation zone (STZ) model of amorphous alloys, and our results may have implications for understanding the role of STZs during creep deformation of MGTFs.

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