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Low Temperature Failure of Al_{90}Fe_7Ta_3 Amorphous Alloys

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Miškuf J., Csach K., Juríková A., Bengus V., Tabachnikova E., Shumilin S., Podolskiy A.

issue 5

823-824

The fractographic analysis was used for the interpretation of ultra-low temperature dependences of yield or fracture stress. Analysis of fracture morphology revealed that dominantly chevron morphology is present and that the failure of this amorphous material initiates at low temperatures at geometrical imperfections of ribbons and these failures are often presented as a premature failure.

Peculiarities of Plastic Deformation of SPD Al-Li Alloy at 0.5 K

100%

Shumilin S., Isaev N., Zabrodin P., Fomenko V., Grigorova T., Geidarov V.

Acta Physica Polonica A

2015

vol. 128

issue 4

536-539

The mechanical properties of Al-Li solid solution were studied in tensile deformation tests at extremely low temperature of 0.5 K. The purpose of this study was to investigate the flow stress and work hardening rate as well as the development of serrated (jump-like) deformation for the polycrystalline samples with different microstructure. The samples obtained by severe plastic deformation via hydroextrusion were initially tensed up to a given intermediate deformation, then unloaded, annealed to modify their microstructure, and once again deformed to fracture. The increase of the grain size and decrease of average dislocation density due to annealing were found responsible for the work hardening rate increases and the flow stress decrease in accordance with the superposition of the Hall-Petch and Taylor contributions. As opposed to the flow stress, the high ductility of the samples remains rather insensitive to the microstructure properties, apparently due to suppressed recovery processes as well as the unstable deformation mode at extremely low temperature. The high ductility makes it possible to compare the work hardening rate and the scale of jump-like plastic deformation along the stress-strain curves for samples with different microstructures. In all cases, the average amplitude of the stress jumps was observed to increase whereas the average work hardening rate decreases with deformation. The observed correlation indicates that the nature of both phenomenons follows from the dislocation density evolution processes.

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2 Acta Physica Polonica A

1 2015

1 2010

2 Shumilin S.

1 Bengus V.

1 Csach K.

1 Fomenko V.

1 Geidarov V.

1 Grigorova T.

1 Isaev N.

1 Juríková A.

1 Miškuf J.

1 Podolskiy A.

1 Tabachnikova E.

1 Zabrodin P.

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Low Temperature Failure of Al_{90}Fe_7Ta_3 Amorphous Alloys

Peculiarities of Plastic Deformation of SPD Al-Li Alloy at 0.5 K