The Low-Temperature Yield Stress Anomaly in Metals and Alloys

Parkhomenko, T. A.; Pustovalov, V. V.

doi:10.1002/pssa.2210740102

Cited by 30 publications

(10 citation statements)

References 37 publications

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“…where (u,,, -uo) = AmkT, as implied by (8). It should be noted that Z here differs entirely from the stress-dependent part of the 'activation energy', which it represents in the well-known equation of the same form as (9), in "classical" interpretations of stress relaxation, e.g.…”

Section: Slip Propagationmentioning

confidence: 98%

“…In a review of the low-temperature flow-stress anomaly in metals and alloys, Parkhomenko and Pustovalov [8] concluded that, while with decreasing temperature inertial effects appeared to assume an increasing importance in plastic deformation, the models of slip-propagation available in the early eighties had not proved adequate to explain the observed occurrence of a peak in the flow stress-temperature relation; only a 'flattening' was to be expected. A synthesis of processes involving thermal activation and, associated with them, others arising from lattice friction acting on dislocations moving with relatively high velocities, was therefore required for a satisfactory description of work-hardening and of the flow-stress anomaly.…”

Section: Introductionmentioning

confidence: 99%

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Nucleation and Dynamic Glide of Dislocations as Co-Determinants of the Low-Temperature Flow-Stress Anomaly and the Stress-Relaxation Rate in Copper and Dilute Brasses between 15 and 300 K

Feltham

Kauser

1992

Phys. Stat. Sol. (a)

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The dependences of the logarithmic stress‐relaxation rate s ≡ − dσ/d 1n(1 + t/t0) of coarse‐grained high‐purity copper and brasses (c = 0.03 to 1.0 at% Zn) on the initial level of the compressive stress, σ0, and on temperature are determined, following incremental pre‐strains of ½ to 1% in the near‐linear work‐hardening stage, at total strains of 2 to 5%. The results are correctly encompassed by the relation s ˜ σ0T(T + Td)−1, representing a stochastic process of “slip nucleation and dynamic glide”, the latter occurring by percolation of dislocations through accessible zones of the glide planes. T outside the bracket refers to the temperature dependence of the nucleation rate, and (T + Td)−1 to the post‐nucleation slip distance. Its length is assumed to be limited by the frictional resistance to the movement of the dislocations, due to phonon scattering (T inside the bracket), and that arising from forest dislocations, solute atoms, etc. (Td). The theory facilitates derivation of the hitherto empirical “stress‐concentration factor” used in descriptions of the low‐temperature flow‐stress anomaly, which is manifest also in the present materials, and provides a clear indication of its origin.

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Section: Slip Propagationmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Nucleation and Dynamic Glide of Dislocations as Co-Determinants of the Low-Temperature Flow-Stress Anomaly and the Stress-Relaxation Rate in Copper and Dilute Brasses between 15 and 300 K

Feltham

Kauser

1992

Phys. Stat. Sol. (a)

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“…При низких температурах в алюминии наблюдается аномально высокая скорость ползучести [7]. Покажем, что на макроуровне при этом происходит разупроч-нение кристалла.…”

Section: рис 6 зависимость напряжения от деформации для области монunclassified

Особенности Движения Дислокаций В Алюминии С Учетом Рельефа Пайерлса В Присутствии Ультразвука

Аракелян¹

2017

Физика Твердого Тела

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Исследовано влияние ультразвука на движение дислокаций Френкеля-Конторовой в алюминии с учетом рельефа Пайерлса. При преодолении барьера Пайерлса дислокация движется с переменной скоростью. Под действием ультразвука различных частот, сопоставимых со временем перехода дислокации в соседнюю долину, меняется длина свободного пробега дислокаций. Получены зависимости напряжения от деформации для больших и малых скоростей деформаций. В обоих случаях имеет место разупрочнение, однако скорость и характер разупрочнения разные. При резонансной частоте уменьшается сопротивление деформированию, укорачивается стадия упрочнения и удлиняется стадия разупрочнения. На графике зависимости коэффици-ента упрочнения от координаты имеются три области, различные по характеру. При резонансной частоте коэффициент упрочнения уменьшается.

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“…2). Such an anomaly is a common observation in metals and alloys at low temperature [19]. In NiO, it may come from an unavoidable contribution of 0 which peaks at 400 °C (Fig.…”

Section: Tests)mentioning

confidence: 99%