Vacancy-assisted hardening in nanostructured metals

Su, Lihong; Lü, Cheng; Tieu, Anh Kiet; He, Lizi; Zhang, Yun; Wexler, David

doi:10.1016/j.matlet.2010.10.090

Cited by 19 publications

(18 citation statements)

References 16 publications

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“…The high vacancy concentration in the sample RT-8 confirms the conclusion of Ref. [3], which also identified a high vacancy concentration in Al deformed by more than 6 RT-ECAP passes. In this case differential scanning calorimetry and XRD were employed.…”

Section: Discussionsupporting

confidence: 89%

“…Dislocations, grain boundaries and their interactions dominate the work-hardening mechanisms in Stages I-IV, while the interaction of vacancy-type defects and dislocations has been regarded as the major work-hardening mechanism in Stage V [2]. In addition, our recent study [3] showed that vacancy-type defects are responsible for unusual phenomena such as annealing-induced hardening and softening by slight deformation in severely deformed Al. Thus, there is significant evidence that vacancy-type defects play an important role during the deformation of UFG materials.…”

Section: Introductionmentioning

confidence: 94%

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Study of vacancy-type defects by positron annihilation in ultrafine-grained aluminum severely deformed at room and cryogenic temperatures

Lü

et al. 2012

Acta Materialia

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. (2012).Study of vacancy-type defects by positron annihilation in ultrafine-grained aluminum severely deformed at room and cryogenic temperatures.Acta Materialia, 60 (10), 4218-4228. Abstract Commercial-purity aluminum was processed by equal-channel angular pressing (ECAP) at room temperature (RT-ECAP) and cryogenic temperature (CT-ECAP) with liquid nitrogen cooling between two successive passes. It was found that the RT-ECAPed samples showed equiaxed microstructure after 4 and 8 ECAP passes, while the CT-ECAPed samples displayed slightly elongated microstructure and slightly smaller grain size. Moreover, the CT-ECAPed samples had higher hardness values than the RT-ECAPed samples subjected to the same amount of deformation. Positron annihilation lifetime spectroscopy (PALS) was used to investigate the evolution of vacancytype defects during the ECAP deformation process. The results showed that three types of defects existed in the ECAPed samples: vacancies associated with dislocations, bulk monovacancies and bulk divacancies. The CT-ECAPed samples had a higher fraction of monovacancies and divacancies. These two types of defects are the major vacancy-type defects that can work as dislocation pinning centers and induce hardening, resulting in higher hardness values in the CT-ECAPed samples. A quantitative relationship between material hardness and the defect concentration and defect diffusion coefficient has been established. Authors

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Section: Discussionsupporting

confidence: 89%

Section: Introductionmentioning

confidence: 94%

Study of vacancy-type defects by positron annihilation in ultrafine-grained aluminum severely deformed at room and cryogenic temperatures

Lü

et al. 2012

Acta Materialia

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“…The specific wear rate and COF measurements show their dependence from sample material chemical composition, sample (surface) hardness as well material wear track surface softening/hardening [21] during wear testing (Fig 5a). Results show that HCV deformed sample in surface was hardened from 77HV0.05 to 90HV0.05 and on the wear track surface from 115 to 126HV0.05, respectively.…”

Section: Resultsmentioning

confidence: 94%

Electrical conductivity and mechanical properties of Cu-0.7wt% Cr and Cu-1.0wt% Cr alloys processed by severe plastic deformation

Kommel¹,

Pokatilov²

2014

IOP Conf. Ser.: Mater. Sci. Eng.

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“…Some hypotheses have been proposed to explain this phenomenon. These hypotheses range from a mechanistic explanation based on the residual stresses created by dislocations [35] or the absorption of vacancies by grain boundaries [36] to a sophisticated model including different mechanisms of strengthening at different stages of deformation [37]. In practice, all of these explanations must incorporate the changing of some structural parameters (grain size, dislocation density, etc.)…”

Section: Discussionmentioning

confidence: 99%

Effect of annealing on wear resistance and electroconductivity of copper processed by high-pressure torsion

et al. 2013

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The influences of annealing temperature on the wear properties and electrical conductivity of Cu were studied after processing by high-pressure torsion (HPT). The annealing of Cu specimens processed by HPT leads to an increase in electroconductivity and a decrease in the wear rate. It is apparent that a nanotribolayer at the surface induced during wear sliding plays a more significant role than the ultrafine-grained structure. A slight increase was observed in the microhardness of HPT copper specimens upon annealing at a relatively low temperature (100°C), and this is most likely due to a change in texture. The annealing leads to an increase in the Taylor factor by *5 %, which is in good agreement with the increase in the microhardness level which is also by *5 %. It is apparent that low-temperature annealing of HPT copper may produce optimal properties of the specimens including high strength and electroconductivity with a lower wear rate.

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Vacancy-assisted hardening in nanostructured metals

Cited by 19 publications

References 16 publications

Study of vacancy-type defects by positron annihilation in ultrafine-grained aluminum severely deformed at room and cryogenic temperatures

Study of vacancy-type defects by positron annihilation in ultrafine-grained aluminum severely deformed at room and cryogenic temperatures

Electrical conductivity and mechanical properties of Cu-0.7wt% Cr and Cu-1.0wt% Cr alloys processed by severe plastic deformation

Effect of annealing on wear resistance and electroconductivity of copper processed by high-pressure torsion

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