Dependence of internal friction of fibre-reinforced and unreinforced AZ91 on heat treatment

Göken, J.; Riehemann, W.

doi:10.1016/s0921-5093(01)01294-1

Cited by 23 publications

(19 citation statements)

References 8 publications

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“…5b) was characterised by a high amount of precipitates. This means a flagrant impoverishment of atoms in the matrix which has a significant impact on the material damping [17].…”

Section: Resultsmentioning

confidence: 99%

Strain-Dependent Damping of Ti-10V-2Fe-3Al at Room Temperature

2016

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The Ti-10V-2Fe-3Al alloy is advantageous over other titanium grades due to its high tensile strength and its high resistance against creep, cracking, and corrosion. The investigated alloy was hammer-forged inducing high strain rates in the material at a temperature of 800• C and underwent different cooling procedures. Three in that way thermomechanically treated specimens were prepared for subsequent study of the vibration behaviour of the material with the help of non-destructive, contact-free acoustic measurements. Resulting time-dependent decaying acoustic signals were analysed to investigate the dependence of the material damping behaviour on the individual downstream thermal treatment procedure and, ultimately, on the microstructural changes.

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“…5b) was characterised by a high amount of precipitates. This means a flagrant impoverishment of atoms in the matrix which has a significant impact on the material damping [17].…”

Section: Resultsmentioning

confidence: 99%

Strain-Dependent Damping of Ti-10V-2Fe-3Al at Room Temperature

2016

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“…It is generally accepted that the thermal stress is very large in the ceramic reinforced metal matrix composite because of the large difference between the coefficients of thermal expansion (CTE) of metals and ceramics, which is also possible to create new dislocations at the interface between the reinforced phase and the metal matrix. The density of newly created dislocations in the vicinity of the reinforced phase can be calculated as [15] T (1 )…”

Section: Combination Of Strengthening Termsmentioning

confidence: 99%

Microstructure and strengthening mechanisms of Mg-6Al-6Nd alloy

Yan

et al. 2010

Rare Metals

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The microstructure and strengthening mechanisms of as-cast Mg-6Al-6Nd alloy were studied. The results show that the addition of 6 wt.% Nd into Mg-6Al alloy leads to the precipitation of Al 11 Nd 3 and Al 2 Nd phases and decrease in the content of Al solid soluted in Mg-Al matrix. The volume fractions of Al 11 Nd 3 and Al 2 Nd phases are 3.64% and 0.34%, respectively. Compared with Mg-6Al alloy, the ultimate strength, yielding strength, and elongation of Mg-6Al-6Nd alloy at room temperature and 175°C are enhanced in some degrees. The strengthening mechanisms of Mg-6Al-6Nd alloy are mainly composed of solid solution strengthening of Al solid soluted in Mg-Al matrix and grain refinement strengthening, dispersion strengthening, and composite strengthening brought by the precipitation of Al 11 Nd 3 phase. The composite strengthening includes the load transfer from the matrix to Al 11 Nd 3 phase and the enhancement of dislocation density due to the geometrical mismatch and thermal mismatch between the matrix and Al 11 Nd 3 phase.

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“…The measured strain-independent damping δ 0 is superimposed by three different kinds of damping [7] : δ 0 =δ t +δ a +δ d (2) where δ t is the thermoelastic damping caused by heat flow from the compressed to the dilated surface [8] , δ a the apparatus damping, and δ d the dislocation damping mainly of dislocation movement origin. Light metals have high thermoelastic damping due to high coefficients of thermal expansion and low thermal conductivity [9] .…”

Section: Strain-independent Dampingmentioning

confidence: 99%

“…It should be noted that the specimens annealed at 453 K and 533 K have a bit higher 4 d δ value than the as-cast specimen. An explanation of this phenomenon may be that some impurity atoms and vacancies will slightly move and leave the dislocation cores during heat treatment [7] , thereby L C will be slightly increased. This effect, however, may be covered by the dissolution of the second phase, which results in increase of number of impurity atoms, when annealing temperature is higher.…”

Section: Strain-independent Dampingmentioning

confidence: 99%

Influence of isochronal heat treatment on damping behavior of AZ61 alloy

Liu

Zi-juan

Zhu

et al. 2007

J Cent. South Univ. Technol.

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Strain amplitude dependence of the logarithmic decrement was measured and studied on an AZ61 magnesium alloy at room temperature. Measurements were carried out before and after isochronal thermal treatment step by step with increasing temperature. For all specimens, the strain dependence of the logarithmic decrement exhibits two regions. At lower strains the logarithmic decrement is strain independent and in the higher strain region it depends strongly on strain amplitude. The strain-independent logarithmic decrement is mainly composed of thermoelastic damping and dislocation damping, which can be explained by Granato-Lücke theory. In addition, the strain-independent logarithmic decrement for the specimens annealed at higher temperatures is a little lower than that for as-cast specimen, and it increases with increasing temperature of heat treatment. Microstructure changes due to heat treatment are responsible for changes of the logarithmic decrement. IntrodutionNumerous problems in engineering are caused by mechanical vibrations, therefore there is a need for lightmass materials that exhibit simultaneously high damping capacity and good mechanical properties, such as a high modulus, a high mechanical strength, good creep resistance or good fatigue resistance. Pure magnesium has the highest damping capacity owing to the easy motion of dislocations at room temperature [1] , while its low strength limits its application as structural material. Introducing alloying elements and precipitates that are able to pin the dislocations can avoid plastic deformation and thereby can increase the tensile strength [2] . Within the magnesium alloys with aluminum and zinc as alloying elements, AZ61 alloy appears. In fact, even if this alloy is widely used in industry, some of its damping (internal friction) and elastic capacities are still not understood.In the present investigation, the influence of isochronal heat treatment on damping behavior of an AZ61 magnesium alloy was studied. ExperimentalThe alloy used was a commercial Mg-Al-Zn alloy obtained through semi-continuous casting with chemical composition of Mg-5.81Al-0.55Zn-0.29Mn (mass fraction, %). Test specimens for damping measurements were machined to bending beams with a length of 30 mm, a width of 3 mm and a thickness of 1 mm. Then the specimens were isochronally annealed for 1 h in a thermostated furnace filled with sublimed sulfur and then quenched in water at room temperature. The annealing temperature ranged from 453 to 773 K and increased in step of 80 K. The damping and elastic properties were measured as a function of the strain amplitude by employing a dynamic mechanical analyzer(DMA) at a vibration frequency of 20 Hz in forced mode at room temperature in air, and the vibration of strain amplitude was increased from 1×10 −5 to 4×10 −3 . In the forced mode and for cases of relatively small damping capacity, the damping capacity (δ, also called logarithmic decrement) is given by [3] :where θ is the phase lag between the strain and the applied stress. The quantitat...

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Dependence of internal friction of fibre-reinforced and unreinforced AZ91 on heat treatment

Cited by 23 publications

References 8 publications

Strain-Dependent Damping of Ti-10V-2Fe-3Al at Room Temperature

Strain-Dependent Damping of Ti-10V-2Fe-3Al at Room Temperature

Microstructure and strengthening mechanisms of Mg-6Al-6Nd alloy

Influence of isochronal heat treatment on damping behavior of AZ61 alloy

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