Abstract
Amplitude dependent internal friction (ADIF) was measured in three AZ magnesium alloys. Two types of experiments were performed: ADIF was measured step by step with the increasing strain amplitude and ADIF was measured after predeformation of samples in torsion. All experiments were done at room temperature. The quality factor was used as a measure of internal friction (IF). The quality factor decreased in the region of smaller amplitudes, and approaching some critical amplitude, εcr, rapidly increased. This critical amplitude increased with increasing maximum strain amplitude and predeformation of samples up to ~6%. Such behavior can be explained by considering mobile solute atoms, which may migrate along the dislocation line in the region of smaller amplitudes and perpendicular to the dislocation line in the region of higher amplitudes. A competition between dragging and depinning of solute atoms with dislocation lines may very well explain the measured dependencies.
Highlights
The lightest commercial structural alloys, magnesium alloys, offer lightweight, high specific stiffness, strength, and good machinability
We studied the influence of predeformation in the compression on the Amplitude dependent internal friction (ADIF) curves with the aim to find out how the changes in the microstructure may affect the internal friction characteristics
Commercial magnesium alloys AZ31, AZ61, and AZ91 were used as an experimental material, supplied by their respective manufacturer in a cast state without heat treatment in the form of ingots
Summary
The lightest commercial structural alloys, magnesium alloys, offer lightweight, high specific stiffness, strength, and good machinability. Due to these properties, magnesium materials are the focus of engineers and designers [1,2,3,4,5], and their applications allow for energy savings in transport facilities. It is necessary to point out that the high damping properties of magnesium alloys are not features that are available for other metallic structural materials [15,16]. We studied the influence of predeformation in the compression on the ADIF curves with the aim to find out how the changes in the microstructure may affect the internal friction characteristics
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