This study investigates yielding behaviour, Hall–Petch relationship and strengthening mechanism of ultrafine-grained Al–Mg binary alloys. Ultrafine-grained Al–Mg samples reveal unusual discontinuous yielding and extra Hall–Petch strengthening. The critical grain size to separate the extra Hall–Petch strengthening from the conventional Hall–Petch strengthening becomes larger as the Mg content is higher, indicating that dislocation sources in the ultrafine-grained structure becomes more difficult to activate by solute atoms of Mg. It is also found that the Lüders elongation in the discontinuous yielding becomes less pronounced by Mg addition, suggesting that enhancement of work hardening ability by addition of solute atoms is effective to avoid the occurrence of unwanted discontinuous yielding in ultrafine-grained metals.
HallEO.The deformation and ageing of mild steel: III discussion of results. Proc Phys Soc B. 1951; 64:747–753.
2.
PetchNJ.The cleavage strength of polycrystals. J Iron Steel Inst. 1953; 174:25–28.
3.
ShawLL.Processing nanostructured materials: an overview. J Metals (JOM). 2000; 52:41–45.
4.
MeyersMAMishraABensonDJ.Mechanical properties of nanocrystalline materials. Prog Mater Sci. 2006; 51:427–556.
5.
ValievRZZhilyaevAPLangdonTG.Bulk nanostructured materials: Fundamentals and applications. Hoboken (NJ): Wiley; 2014.
6.
YuCYKaoPWChengCP.Transition of tensile deformation behaviors in ultrafine-grained aluminum. Acta Mater. 2005; 53:4019–4028.
7.
KamikawaNHuangXTsujiNStrengthening mechanisms in nanostructured high-purity aluminium deformed to high strain and annealed. Acta Mater. 2009; 57:4198–4208.
8.
LeGMGodfreyAHansenN.Structure and strength of aluminum with sub-micrometer/micrometer grain size prepared by spark plasma sintering. Mater Des. 2013; 49:360–367.
9.
KamikawaKHirochiTFuruharaT.Strengthening mechanisms in ultrafine-grained and sub-grained high-purity aluminum. Metall Mater Trans A. 2019; 50:234–248.
10.
ZhuKNGodfreyAHansenNMicrostructure and mechanical strength of near- and sub-micrometre grain size copper prepared by spark plasma sintering. Mater Des. 2017; 117:95–103.
11.
GaoSChenMChenSYielding behavior and its effect on uniform elongation of fine grained IF steel. Mater Trans. 2014; 55:73–77.
12.
GaoSChenMJoshiMYielding behavior and its effect on uniform elongation in IF steel with various grain sizes. J Mater Sci. 2014; 49:6536–6542.
13.
HuangXTsujiNHansenN.Hardening by annealing and softening by deformation in nanostructured metals. Science. 2006; 312:249–251.
14.
VishnuPMohanRRSangeethaaEKA review on processing of aluminium and its alloys through equal channel angular pressing die. Materials Today: Proceedings. 2020; 21:212–222.
15.
ZhouDWangHSaxeyDWHall–Petch slope in ultrafine grained Al-Mg alloys. Metall Mater Trans A. 2019; 50:4047–4057.
16.
MondolfoLF.Aluminium alloys: structure and properties. London: Butter Worths; 1976.
17.
SaitoYUtsunomiyaHTsujiNNovel ultra-high straining process for bulk materials—development of the accumulative roll-bonding (ARB) process. Acta Mater. 1999; 47:579–583.
18.
KamikawaNTsujiNHuangXQuantification of annealed microstructures in ARB processed aluminum. Acta Mater. 2006; 54:3055–3066.
19.
HumphreysFJHatherlyM.Recrystallization and related annealing phenomena. 2nd ed. Oxford: Elsevier; 2004.
20.
DuckhamAKnutsenRDEnglerO.Influence of deformation variables on the formation of copper-type shear bands in Al–1Mg. Acta Mater. 2001; 49:2739–2749.
21.
SheikhH.Role of shear banding on the microtexture of an Al–Mg alloy processed by hot/high strain rate accumulative roll bonding. Scripta Mater. 2011; 64:556–559.
22.
DugganBJHatherlyMHutchinsonWBDeformation structures and textures in cold-rolled 70:30 brass. Metal Sci. 1978; 12:343–351.
23.
EnglerO.An EBSD local texture study on the nucleation of recrystallization at shear bands in the alloy Al-3%Mg. Scripta Mater. 2001; 44:229–236.
24.
DuckhamAEnglerOKnutsenRD.Moderation of the recrystallization texture by nucleation at copper-type shear bands in Al-1Mg. Acta Mater. 2002; 50:2881–2893.
25.
DieterGE.Mechanical Metallurgy. SI metric Edition. New York (NY): McGraw-Hill Company; 1988.
26.
Ait-AmokhtarHBoudrahemSFressengeasC.Spatiotemporal aspects of jerky flow in Al–Mg alloys, in relation with the Mg content. Scripta Mater. 2006; 54:2113–2118.
27.
WenWMorrisJG.An investigation of serrated yielding in 5000 series aluminum alloys. Mater Sci Eng A. 2003; 354:279–285.
28.
WenWMorrisJG.The effect of cold rolling and annealing on the serrated yielding phenomenon of AA5182 aluminum alloy. Mater Sci Eng A. 2004; 373:204–216.
29.
JobbaMMishraRKNiewczasM.Flow stress and work-hardening behaviour of Al-Mg binary alloys. Int J Plast. 2015; 65:43–60.
30.
MostafaeiMA.Serrated yielding behavior after cold and hot rolling of a high Mg content Al–Mg alloy. J Alloys Comp. 2019; 811:1-6, Article 151997.
31.
HöppelHWMayJGökenM.Enhanced strength and ductility in ultrafine-grained aluminium produced by accumulative roll bonding. Adv Eng Mater. 2004; 6:781–784.
BachJStoiberMSchindlerLDeformation mechanisms and strain rate sensitivity of bimodal and ultrafine-grained copper. Acta Mater. 2020; 186:363–373.
34.
ZolotorevskyNYSoloninANChuryumovAYStudy of work hardening in deforming quenched and naturally aged Al-Mg and Al-Cu alloys. Mater Sci Eng A. 2009; 502:111–117.
35.
TakedaKNakadaNTsuchiyamaTEffect of interstitial elements on Hall–Petch coefficient of ferritic iron. ISIJ Int. 2008; 48:1122–1125.
36.
TakakiSAkamaDNakadaNEffect of grain boundary segregation of interstitial elements on Hall–Petch coefficient in steels. Mater Trans. 2014; 55:28–34.
37.
ShaGYaoLLiaoXSegregation of solute elements at grain boundaries in an ultrafine grained Al–Zn–Mg–Cu alloy. Ultramicroscopy. 2011; 111:500–505.
38.
DevarajAWangWVemuriRGrain boundary segregation and intermetallic precipitation in coarsening resistant nanocrystalline aluminum alloys. Acta Mater. 2019; 165:698–608.
39.
FriedelJ.Dislocations. New York (NY): Pergamon Press; 1964.
40.
HigashiK.New innovations in alchemy dreamed by the first principle—the latter part. J Jpn Inst Light Metals. 2010; 60:458–466.
41.
KayeGWCLabyTH.Tables of physical and chemical constants. 14th ed. London: Longman; 1973.
42.
HansenNHuangX.Microstructure and flow stress of polycrystals and single crystals. Acta Mater. 1998; 46:1827–1836.
