Low Temperature Physics: 45, 811 (2019); https://doi.org/10.1063/1.5111311
Fizika Nizkikh Temperatur: Volume 45, Number 7 (July 2019), p. 947-957    ( to contents , go back )

Low-temperature feature of grain-boundary hardening of nanocrystalline titanium

R.V. Smolianets and V.A. Moskalenko

B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine 47 Nauky Ave., Kharkiv 61103, Ukraine
E-mail: smoljanets@ilt.kharkov.ua
pos Анотація:

Received December 27, 2018, revised February 12, 2019published online May 28, 2019

Abstract

The dependencies of the yield strength σ0.2 of titanium on the grain size d, varying in the micro and nanometer ranges, under tension in the temperature range 4.2–395 K was studied. It was found that at temperatures below ~ 180 K, the dependencies of σ0.2(d) are not described by the classical Hall–Petch relation, deviating at the nanometer size d towards higher voltages. The features of grain boundary hardening observed at low temperatures are explained using theoretical models, according to which in the nanometer range of grains the diameter of the dislocation loop originating at the grain boundary is proportional to d, and the nucleation stress σ ~ 1/d. An estimate of the critical value of dnc was obtained, below which the ratio σ0.2 ~ 1/d holds at a fixed temperature. It is established that with an increase in the temperature of the experiment, the value of dnc decreases.

Key words: grain boundary hardening, Hall–Petch relationship, low temperatures, nanocrystalline titanium VT1-0.

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