Strain-amplitude-dependent mechanical loss at intermediate temperatures in a Ni-3(Al, Ta) single crystal

Dislocation dynamics in a Ni-3(Al, Ta) single-crystal alloy have been studied by means of mechanical spectroscopy at intermediate temperatures, that is in the temperature range of the flow stress anomaly. The mechanical loss of specimens predeformed at 300 K was found to be strongly dependent on temperature, pre-deformation level and heating rate. Thermal cycling (heating-cooling) and ageing experiments were also performed, which provided additional information about the annealing time dependence of the mechanical loss, elastic modulus of the material and plastic deformation of the specimens. The obtained results can be explained by a combination of two phenomena simultaneously occurring as the temperature is increased from 300 to about 500 K exhaustion of the mobile dislocation parts (superkinks) and pinning of the screw dislocation segments via cross-slip from the (111) onto the (010) planes.

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Nadine Baluc, Robert Schaller, Joël Bonneville
1999
Journal paper

Abstract

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https://infoscience.epfl.ch/record/119699?ln=en

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Related concepts (3)

Temperature

Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied on various reference points and thermometric substances for definition. The most common scales are the Celsius scale with the unit symbol °C (formerly called centigrade), the Fahrenheit scale (°F), and the Kelvin scale (K), the latter being used predominantly for scientific purposes.

Single crystal

In materials science, a single crystal (or single-crystal solid or monocrystalline solid) is a material in which the crystal lattice of the entire sample is continuous and unbroken to the edges of the sample, with no grain boundaries. The absence of the defects associated with grain boundaries can give monocrystals unique properties, particularly mechanical, optical and electrical, which can also be anisotropic, depending on the type of crystallographic structure.

Dislocation

In materials science, a dislocation or Taylor's dislocation is a linear crystallographic defect or irregularity within a crystal structure that contains an abrupt change in the arrangement of atoms. The movement of dislocations allow atoms to slide over each other at low stress levels and is known as glide or slip. The crystalline order is restored on either side of a glide dislocation but the atoms on one side have moved by one position. The crystalline order is not fully restored with a partial dislocation.