Fizika Nizkikh Temperatur: Volume 44, Number 11 (November 2018), p. 1540-1548 ( to contents , go back )
Stress relaxation in ultra-fine-grained copper at low homologous temperatures
N.V. Isaev, T.V. Hryhorova
B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine 47 Nauky Ave., Kharkiv 61103, Ukraine
О.О. Galkin Donetsk Institute of Physics and Engineering, 46 Nauki Ave., Kyiv 03680, Ukraine
G.V. Kurdyumov Institute for Metal Physics, NASU, 36 Acad. Vernadsky Boulevard, Kyiv 03680, Ukraine
Received May 23, 2018, published online September 26, 2018
Temperature and strain-rate sensitivities of flow stress of ultra-fine grained (UFG) copper, prepared by equal-channel angular hydroextrusion, were studied. Tensile tests and stress relaxation tests were carried out in the temperature range 77–295 K. As temperature increase, flow stress decrease monotonously whereas activation volume reaches the maximum value of ~190b3 at temperature ~200 К. These experimental results are discussed in terms of two mechanisms of thermally activated plastic deformation: “forest” intersection and dynamic recovery, which able to significantly affect the kinetics of stress relaxation in UFG copper.
Key words: ultrafine grained metal, mechanical properties, deformation mechanism, activation volume.