Abstract
Microstructural features of a duplex-phase Zr-2.5Nb alloy were investigated in detail using electron channeling contrast (ECC) imaging and electron backscatter diffraction (EBSD) technique in an emission gun scanning electron microscope (FEGSEM). The excellent resolution provided by the FEGSEM promises the combined utilization of both techniques to be quite adequate for characterizing the duplex-phase microstructures. Results show that the microstructure of the Zr-2.5Nb alloy is composed of bulk a grains (majority) in equiaxed or plate shape and thin β films (minority) surrounding the bulk grains, with their average grain size and thickness measured to be 1.4 µm and 72 nm, respectively. Analyses on α-grain boundaries reveal a number of low angle boundaries, most of which belong to deformation-induced dislocation boundaries. Measurements on relative proportions of various Burgers boundaries suggest very weak (if any) variant selection during β → α cooling, which should be related to deformation-induced higher nucleation rate of α phases. Compared to earlier attempts, more satisfactory indexing of fine β phases (down to nanoscale) is attained by the FEGSEM-based EBSD. Examples are presented to clearly reveal well-obeyed Burgers orientation relationships between adjacent a and β phases. Finally, it is deduced that continuing application of the FEGSEM-based EBSD to duplex-phase Zr alloys could help clarify controversies like the deformation priority of the two phases.
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References
Zinkle S J, Was G S. Materials challenges in nuclear energy. Acta Mater, 2013, 61: 735–758
Jeong Y H, Park S Y, Lee M H, et al. Out-of-pile and in-pile perfomance of advanded zirconium alloys (HANA) for high burn-up fuel. J Nucl Sci Technol, 2006, 43: 977–983
Toffolon-Masclet C, Guilbert T, Brachet J C. Study of secondary intermetallic phase precipitation/dissolution in Zr alloys by high temperature-high sensitivity calorimetry. J Nucl Mater, 2008, 372: 367–378
Cai S, Daymond M R, Holt R A. Deformation of high β-phase fraction Zr–Nb alloys at room temperature. Acta Mater, 2012, 60: 3355–3369
Yang Z N, Zhang F C, Qu L, et al. Formation of duplex microstructure in Zr–2.3Nb alloy and its plastic behaviour at various strain rates. Int J Plasticity, 2014, 54: 163–177
Yang Z N, Zhang F C, Liu F C, et al. Achieving high strength and toughness in a Zr-2.3Nb alloy by the formation of duplex microstructure. Mater Des, 2012, 40: 400–406
Hiwarkar V D, Sahoo S K, Mani krishna K V, et al. Coarsening of second phase in a two-phase Zr–2.5Nb: On the role of phase boundaries. Acta Mater, 2009, 57: 5812–5821
Hovington P, Pinard P T, Lagacé M, et al. Towards a more comprehensive microstructural analysis of Zr–2.5Nb pressure tubing using image analysis and electron backscattered diffraction (EBSD). J Nucl Mater, 2009, 393: 162–174
Romero J, Preuss M, Quinta da Fonseca J. Texture memory and variant selection during phase transformation of a zirconium alloy. Acta Mater, 2009, 57: 5501–5511
Yao M Y, Zhou B X, Li Q, et al. A superior corrosion behavior of zircaloy-4 in lithiated water at 360°C/18.6 MPa by beta-quenching. J Nucl Mater, 2008, 374: 197–203
Kumar M K, Samajdar I, Venkatramani N, et al. Explaining absence of texture development in cold rolled two-phase Zr–2.5 wt% Nb alloy. Acta Mater, 2003, 51: 625–640
Sahoo S K, Hiwarkar V D, Jain L, et al. Deformed microstructures of two-phase Zr–2.5Nb alloy: Effects of the second phase hardness. J Nucl Mater, 2010, 404: 222–230
Cai S, Daymond M R, Khan A K, et al. Elastic and plastic properties of beta(Zr) at room temperature. J Nucl Mater, 2009, 393: 67–76
Muránsky O, Daymond M R, Bhattacharyya D, et al. Load partitioning and evidence of deformation twinning in dual-phase fine-grained Zr–2.5%Nb alloy. Mater Sci Eng A, 2013, 564: 548–558
Randle V. Electron backscatter diffraction: Strategies for reliable data acquisition and processing. Mater Charact, 2009, 60: 913–922
Zaefferer S. A critical review of orientation microscopy in SEM and TEM. Cryst Res Technol, 2011, 46: 607–628
Holt R A, Zhao P. Micro-texture of extruded Zr–2.5Nb tubes. J Nucl Mater, 2004, 335: 520–528
Hiwarkar V D, Sahoo S K, Samajdar I, et al. Annealing of cold worked two-phase Zr-2.5 Nb-associated microstructural developments. J Nucl Mater, 2009, 384: 30–37
Zaefferer S, Elhami N N. Theory and application of electron channelling contrast imaging under controlled diffraction conditions. Acta Mater, 2014, 75: 20–50
Humphreys F J. Review-grain and subgrain characterisation by electron backscatter diffraction. J Mater Sci, 2001, 36: 3833–3854
Chai L J, Luan B F, Gao S S, et al. Study of precipitate evolution and recrystallization of β-quenched Zr-Sn-Nb-Fe-Cr-Cu alloy during aging. J Nucl Mater, 2012, 427: 274–281
Chai L, Chen B, Zhou Z, et al. A special twin relationship or a common Burgers misorientation between α plates after β quenching in Zr alloy? Mater Charact, 2015, 104: 61–65
Jeong Y H, Lee K O, Kim H G. Correlation between microstructure and corrosion behavior of Zr-Nb binary alloy. J Nucl Mater, 2002, 302: 9–19
Tewari R, Srivastava D, Dey G K, et al. Microstructural evolution in zirconium based alloys. J Nucl Mater, 2008, 383: 153–171
Choo K N, Kang Y H, Pyun S I, et al. Effect of composition and heat treatment on the microstructure and corrosion behavior of Zr-Nb alloys. J Nucl Mater, 1994, 209: 226–235
Burgers W G. On the process of transition of the cubic-body-centered modification into the hexagonal-close-packed modification of zirconium. Physica, 1934, 1: 561–586
Chai L, Luan B, Zhang M, et al. Experimental observation of 12 α variants inherited from one β grain in a Zr alloy. J Nucl Mater, 2013, 440: 377–381
Chai L, Luan B, Xiao D, et al. Microstructural and textural evolution of commercially pure Zr sheet rolled at room and liquid nitrogen temperatures. Mater Design, 2015, 85: 296–308
Chun Y B, Battaini M, Davies C H J, et al. Distribution characteristics of in-grain misorientation axes in cold-rolled commercially pure titanium and their correlation with active slip modes. Metall Mater Trans A, 2010, 41A: 3473–3487
Akhtar A. Basal slip in zirconium. Acta Metall, 1973, 21: 1–11
Hughes D A, Hansen N. Exploring the limit of dislocation based plasticity in nanostructured metals. Phys Rev Lett, 2014, 112: 135504
Chauvy C, Barberis P, Montheillet F. Microstructure transformation during warm working of beta-treated lamellar zircaloy-4 within the upper alpha-range. Mater Sci Eng A, 2006, 431: 59–67
Daymond M R, Holt R A, Cai S, et al. Texture inheritance and variant selection through an hcp–bcc–hcp phase transformation. Acta Mater, 2010, 58: 4053–4066
Gey N, Humbert M, Gautier E, et al. Study of the β→α variant selection for a zircaloy-4 rod heated to the β transus in presence or not of an axial tensile stress. J Nucl Mater, 2004, 328: 137–145
Kumar N A P K, Szpunar J A. Ebsd studies on microstructure and crystallographic orientation of delta-hydrides in zircaloy-4, Zr-1% Nb and Zr-2.5% Nb. Mater Sci Eng A, 2011, 528: 6366–6374
Cabibbo M, Zherebtsov S, Mironov S, et al. Loss of coherency and interphase α/β angular deviation from the Burgers orientation relationship in a Ti–6Al–4V alloy compressed at 800°C. J Mater Sci, 2013, 48: 1100–1110
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Chai, L., Wang, S., Luan, B. et al. Electron backscatter diffraction investigation of duplex-phase microstructure in a forged Zr-2.5Nb alloy. Sci. China Technol. Sci. 59, 673–679 (2016). https://doi.org/10.1007/s11431-016-6019-0
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DOI: https://doi.org/10.1007/s11431-016-6019-0