A microstructural work hardening model based on three internal state variables

Goerdeler, M.; Gottstein, Günter

doi:10.1016/s0921-5093(00)01728-7

Cited by 56 publications

(20 citation statements)

References 13 publications

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“…Hence, the usual description of flow stress with macroscopic state variables (strain and overall chemical composition) is unsatisfactory in certain cases [3].…”

mentioning

confidence: 99%

Quench-induced precipitates in Al–Si alloys: Calorimetric determination of solute content and characterisation of microstructure

et al. 2015

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The present study introduces an experimental approach to investigate mechanical properties of well-defined nonequilibrium states of Al-Si alloys during cooling from solution annealing. The precipitation behaviour of binary Al-Si alloys during the cooling process has been investigated in a wide cooling rate range (2 K/s-0.0001 K/s) with differential scanning calorimetry (DSC). To access the low cooling rate range close to equilibrium an indirect DSC measurement method is introduced. Based on the enthalpy change measured by DSC a physically-based model for the calculation of remaining solute Si amount as function of temperature and cooling rate is presented.Microstructural analyses via light optical microscopy, scanning electron microscopy, atom probe tomography 50 and X-ray diffraction have been performed to evaluate the introduced model and for information on cooling rate dependent precipitate formation. It was found that quench-induced particles of different morphology are formed during cooling. Thermomechanical analyses on clearly distinct undercooled Al-Si states show that flow stress during cooling is dependent on temperature as well as cooling rate. The mechanical behaviour is therefore influenced by solute Si content and quench-induced precipitates.

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“…Hence, the usual description of flow stress with macroscopic state variables (strain and overall chemical composition) is unsatisfactory in certain cases [3].…”

mentioning

confidence: 99%

Quench-induced precipitates in Al–Si alloys: Calorimetric determination of solute content and characterisation of microstructure

et al. 2015

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“…This phenomenon decreases the increasing rate of mobile dislocation density as a result of annihilation process, formation of locks, and the formation of dipoles. 13 On the other hand, with dislocation density variations, no appreciable reduction can be observed in the yield strength, even beyond 4 passes, by increasing the clad layer thickness (Fig. 2).…”

Section: Resultsmentioning

confidence: 91%

DEVELOPMENT OF CRYSTALLOGRAPHIC TEXTURE AND GRAIN REFINEMENT IN THE ALUMINUM LAYER OF CU-AL-CU TRI-LAYER COMPOSITE DEFORMED BY EQUAL CHANNEL ANGULAR EXTRUSION

Tolaminejad

Taheri

Shahmiri

et al. 2012

Int. J. Mod. Phys. Conf. Ser.

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The present research is concerned with the aluminum layer of a loosely packed tri-layer copperaluminum-copper composite deformed by ECAE process. Electron back scattered diffraction (EBSD), transmission electron microscope, and X-ray technique were employed to investigate the detailed changes occurring in the microtexture, microstructure (cell size and misorientation), and dislocation density evolution during consecutive passes of ECAE process performed on the composite based on route Bc. According to tensile test results, the yield stress of the aluminum layer was increased significantly after application of ECAE throughout the four repeated passes and then slightly decreased. An ultrafine grain size within the range of 500-600 nm was obtained in the Al layer by increasing the thickness of copper layers. It was observed that the reduction of grain size in the aluminum layer is nearly 57% more than that of an ECAE-ed single layer aluminum billet. Also, the grain refinement of the aluminum layer is accelerated throughout 8 passes. This observation was attributed to the higher rate of dislocation interaction, cell formation and texture development during the ECAE of the composite compared to those of the single billet.

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“…e decrease in the dislocation density after severe plastic deformation was also reported along with softening caused by the dislocation annihilation [15][16][17][18][19][20][21]; for example, after four passes of equal-channel angular pressing (ECAP) of pure copper, a decrease in the dislocation density was reported by Della Torre et al [11]. According to their result, it is suggested that the decrease of stress field is also related to the operation of recovery mechanism, causing an increase in the dislocationfree grains [11].…”

Section: Advances In Materials Science and Engineeringmentioning

confidence: 86%

Transition of Dislocation Structures in Severe Plastic Deformation and Its Effect on Dissolution in Dislocation Etchant

Rifai

Bagherpour

Yamamoto

et al. 2018

Advances in Materials Science and Engineering

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Transition of dislocation structures in ultrafine-grained copper processed by simple shear extrusion (SSE) and its effects on dissolution were manifested by simple immersion tests using a modified Livingston dislocation etchant, which attacks dislocations and grain boundaries selectively. e SSE process increased the internal strain evaluated by X-ray line broadening analysis until eight passes but decreased it with further extrusion until twelve passes. e weight loss in the immersion tests reflected the variation in the internal strain: namely, it increased until eight passes and then decreased with further extrusion to twelve passes. Taking our previous report on microstructural observation into account, it is suggested that variation in the internal strain is caused by both the variation in dislocation density and structural change of grain boundaries from equilibrium to nonequilibrium states or vice versa. Decreased dislocation density and structural change back to equilibrium state of grain boundaries in very high strain range by possibly dynamic recovery as pointed out by Dalla Torre were validated by X-ray and dissolution in the modified Livingston etchant in addition to the direct observation by TEM reported in our former report.

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A microstructural work hardening model based on three internal state variables

Cited by 56 publications

References 13 publications

Quench-induced precipitates in Al–Si alloys: Calorimetric determination of solute content and characterisation of microstructure

Quench-induced precipitates in Al–Si alloys: Calorimetric determination of solute content and characterisation of microstructure

DEVELOPMENT OF CRYSTALLOGRAPHIC TEXTURE AND GRAIN REFINEMENT IN THE ALUMINUM LAYER OF CU-AL-CU TRI-LAYER COMPOSITE DEFORMED BY EQUAL CHANNEL ANGULAR EXTRUSION

Transition of Dislocation Structures in Severe Plastic Deformation and Its Effect on Dissolution in Dislocation Etchant

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