Threshold Stress for Superplastic Flow in the Zn&amp;ndash;Al Eutectoid Alloy

Tandon, S.; Murty, G. S.

doi:10.2320/matertrans1989.34.319

Cited by 19 publications

(19 citation statements)

References 12 publications

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“…2b, was about 0.26. This value is lower than that reported for the Zn-22Al alloy (m = 0.4-0.5) [1,2,[5][6][7][8][9][10]. Figure 3 illustrates the variation in final length of specimens as a function of temperature and strain rate, Fig.…”

Section: Initial Microstructurecontrasting

confidence: 74%

“…10 -3 s -1 ). At this rate, the flow stress Zinalco alloy increases up to 600 % compared with the reported value of the Zn-22Al alloy [1,2,[5][6][7][8][9][10].…”

Section: Initial Microstructurementioning

confidence: 42%

“…Classical example of a superplastic material is the Zn-Al eutectoid alloy (Zn-22Al) [1,2]. The maximum strain attainable during tensile deformation of this alloy depends critically on the strain rate, testing temperature, and the initial grain size [1][2][3][4][5][6][7][8][9][10]. Strains up to 3,000 % have been observed in a region where the relationship between flow stress and strain rate exhibits a maximum slope (region II) [1][2][3][4][5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 98%

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Superplastic behavior of Zn–Al eutectoid alloy with 2 % Cu

2012

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The effects of deformation temperature and strain rate on the superplastic behavior of the Zn-21Al-2Cu alloy (Zinalco alloy) were investigated by uniaxial tensile tests. Results were compared with those of the Zn22Al eutectoid alloy without Cu. It was observed that additions of 2 % Cu leads to a decrease of the maximum strain attainable from 2600 % to 1000 %. The maximum strain in Zinalco alloy is obtained at lower strain rates. The presence of Cu increases the values of flow stress up to 600 % compared with those reported in the Zn-22Al alloy. Grain size sensitivity (p), true activation energy (Q t ), and constant A of the constitutive equation were not affected by presence of Cu unlike the stress exponent (n) which increased from 2.5 to 3.9. The main effect of Cu was to decrease the plastic flow stability of the Zn-22Al alloy.The results indicate that presence of Cu in the Zinalco alloy causes a hardening effect at low strain rates leading to a decrease in the strain rate sensitivity which promotes the formation and growth of sharp necks. Microstructural characterization suggests that the large deformations at necking could possibly be due to the substantial elongation capability of the Zn-rich phase (g).

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Section: Initial Microstructurecontrasting

confidence: 74%

“…10 -3 s -1 ). At this rate, the flow stress Zinalco alloy increases up to 600 % compared with the reported value of the Zn-22Al alloy [1,2,[5][6][7][8][9][10].…”

Section: Initial Microstructurementioning

confidence: 42%

Section: Introductionmentioning

confidence: 98%

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Superplastic behavior of Zn–Al eutectoid alloy with 2 % Cu

2012

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“…The microstructural features were a little different from those reported previously; the material used in the present study was very unique. 8,27,28) Therefore, it is necessary to investigate the effects of these features on the deformation behavior of nanocrystalline Zn particles.…”

Section: Microstructuresmentioning

confidence: 99%

“…It has been reported that the m-value of Zn-22%Al alloys at elevated temperature exhibited 0.5 (n = 2) in the intermediate strain rate regime and from 0.25 to 0.2 (n = 4-5) in the high strain rate regime. [27][28][29][30][31][32][33][34] The grain boundary sliding (GBS) could be expected to occur with an m-value of 0.5. On the other hand, dislocation climb and glide controlled by climb could be expected to occur with an m-value of 0.25 to 0.2.…”

Section: Strain Rate Dependence Of Flow Stress and Elongationmentioning

confidence: 99%

Room Temperature Deformation Behavior of Zn-22 mass%Al Alloy with Nanocrystalline Structure

et al. 2002

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The deformation behavior near room temperature in Zn-22 mass%Al alloy including nanocrystalline structure produced with Thermo Mechanical Controlling Process (TMCP) technology has been characterized over a wide range of strain rates from 10 −6 to 10 −1 s −1 at temperatures from 273 to 473 K. The microstructure of TMCP produced Zn-22 mass%Al alloy had both a random distribution of equiaxed Al-rich and Zn-rich phases with grain size of 1.3 µm and many nanocrystalline Zn particles in Al-rich phases. Since the flow stress in the deformation near room temperature was much larger than that in superplastic deformation and a maximum m value is only 0.3 (n = 3) at low strain rates below 10 −5 s −1 , the pure superplastic behavior may not be observed near room temperature. However it is noted that the large elongation of ∼ 200% was observed at 10 −5 s −1 . From microstructural observations of the specimens tested in the condition with the m value of 0.3 near room temperature, furthermore, it is considered that grain boundary sliding (GBS) is the dominant deformation process, and the specimen may be fractured by cavitation as well as the conventional superplastic materials. Therefore, it seems that the various factors contribute to the deformation flow at room temperature.

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