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Yuan G.,University of Bolton | Zhang L.,CAS Shenyang Institute of Metal Research | Yue Q.,State Nuclear Bao Ti Zirconium Industry Company | Gu H.,CAS Shenyang Institute of Metal Research | And 2 more authors.
Materials Chemistry and Physics | Year: 2015

The β phase precipitates in a Zr-1Nb alloy annealed at 600°C and 700°C (below and above the monotectoid temperature, respectively) for 3h were investigated by transmission electron microscopy. It was found that the uniformly distributed β phase obtained at 600°C was spherical, with diameter of 30-60nm, volume fraction of ~2.5% and Nb content of ~68wt.%. However, the β phase obtained at 700°C was stick-shaped, with ~100nm in diameter and ~300nm in length, volume fraction of ~9.8% and Nb content ~10wt.%. The distinctions in volume fractions and compositions were consistent with the lever rule of the Zr-Nb phase diagram. The distinction in shapes resulted from the change in the interfacial structure, which depended on the lattice misfit. The orientation relationship between α matrix and stick-shape β precipitates satisfied Burgers' orientation relationship, i.e., (101- 0)α//(11- 2)β for the broad face, (0001)α//(110)β for the side facet and (112- 0)α//(1-11)β for the edge. The outline of the stick-shaped β precipitates was composed of straight and curved interfaces, and the broad faces and side facets together formed the straight interface, and the edges formed the curved one. As the Nb content of β phase increased, the lattice misfits on broad face and side facet increased and their interfacial structures changed from coherent (obtained at 700°C) into incoherent (obtained at 600°C), and the misfits of edge decreased, and their interfacial structures were always incoherent for the two heat treatments. Therefore, the curved interfaces had a higher growth rate than the straight interfaces at 700°C and stick-like β phase precipitate was formed. While the three planes have a comparable growth rate at 600°C and spherical β phase precipitate was formed. © 2015 Elsevier B.V. Source

Liang J.,Guangxi University for Nationalities | Liang J.,Queens University | Zhang M.,Guangxi University for Nationalities | Zhang M.,Guangxi University | And 5 more authors.
Journal of Nuclear Materials | Year: 2015

Phase equilibria of the Zr-Nb-Fe system at 700 °C were determined by using X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). Previously reported ternary compounds, cubic Ti2Ni type (ZrNb)2Fe and hexagonal MgZn2 type Zr(NbFe)2, were confirmed. In the zirconium rich corner, equilibria of αZr with βZr and (ZrNb)2Fe, βZr with (ZrNb)2Fe and Zr(NbFe)2, and β-Zr with Zr(Nb,Fe)2 and βNb, were determined. Two four-phase invariant reactions, (ZrNb)2Fe + βZr → αZr + Zr(NbFe)2 and βZr → αZr + Zr(NbFe)2 + βNb, were revealed. A partial reaction scheme was proposed for the zirconium rich alloys. Close to the Nb-Fe side, NbFe phase were revealed to co-exist with (Zr1-xNbx)2Fe rather than Zr(NbFe)2. © 2015 Elsevier B.V. All rights reserved. Source

Qiao K.,Xian University of Architecture and Technology | Wang W.,Xian University of Architecture and Technology | Wu N.,State Nuclear Bao Ti Zirconium Industry Company | Li T.,Xian University of Architecture and Technology | Wang K.,Xian University of Architecture and Technology
Jinshu Rechuli/Heat Treatment of Metals | Year: 2016

Al/Cu clad plates were joined by friction stir welded (FSW) and the effect of welded speed on mechanical properties and microstructure of nugget zone was investigated. The results show that the distribution of aluminum and copper in weld area presents a laminate character, and the grain size in this zone decreases with the increase of the welded speed. The average microhardness of Cu layer in the nugget zone is 88 HV0.2 accounting for 71.06% of basal metal at the welded speed of 95 mm/min. The average microhardness of the Al layer exceeds the as-received metal to 35 HV0.2 and the tensile strength is 115.22 MPa in the nugget zone when the welded speed is 47.5 mm/min. With the increase of welded speed, tensile strength and elongation decrease, and the fracture surface of tensile specimen is characterized by a cleavage fracture. © 2016, Editorial Office of "Jinshu Rechuli". All right reserved. Source

Xu Q.,Shanghai University | Huang J.,Shanghai University | Yao M.,Shanghai University | Peng S.,State Nuclear Bao Ti Zirconium Industry Company | And 4 more authors.
Xiyou Jinshu Cailiao Yu Gongcheng/Rare Metal Materials and Engineering | Year: 2015

To study the effect of S on the second phase particles (SPPs) of zirconium alloys, alloy samples were prepared by adding different contents of S (26~570 μg/g) into Zr-0.70Sn-0.35Nb-0.30Fe alloys. SEM and TEM with EDS were used to investigate the composition and crystalline structure of SPPs. The results show that in Zr-0.70Sn-0.35Nb-0.30Fe alloy, there exists Zr(Nb, Fe)2 SPPs with hexagonal close packed structure, while in the alloys containing S, orthogonal Zr3Fe SPPs appear besides Zr(Nb, Fe)2 SPPs and the Zr3Fe SPPs increase in amount with increasing S content. Zr9S2 SPPs occur when the S content reaches 190 μg/g, and also increase in amount with further increasing S content. The ratio of Nb/Fe decreases with the increase of SPPs' size in the same zirconium alloy. It is indicated that the S content dissolving in α-Zr matrix is between 26 μg/g and 190 μg/g for the alloys in this study and the excess S dissolving in α-Zr matrix is precipitated as Zr9S2 SPPs rather than entering into other SPPs. ©, 2015, Rare Metals Materials and Engineering Press. All right reserved. Source

Huang Y.,Chongqing University | Zhang L.,Chongqing University | Huang Z.,Chongqing University | Guo Q.,State Nuclear Bao Ti Zirconium Industry Company
Chongqing Daxue Xuebao/Journal of Chongqing University | Year: 2012

Abrasive belt grinding experiments of Zr-4 nuclear power tube are carried out by using three different abrasive belts with same size, and the interactive generating mechanism between abrasive and workpiece is analyzed, the main factors of material removal rate and surface roughness of Zr-4 alloys are obtained. With the help of the advanced test facilities, the abrasive grain abrasion and surface topography of the workpiece are observed. The metallographic structure and microhardness of the layer of burnt surface during Zr-4 alloys Grinding are analyzed. Some conclusions are given as follows: the material removal rate and surface roughness are mainly affected by the factors of belt speed, grinding pressure, hardness of the contact wheel and abrasive type, of which, the belt speed is the strongest factor. The adhesion wear of the Zirconium corundum and aluminium oxide abrasive grit is more serious, the most important wear form of silicon carbide is abrasion wear. With the onset of grinding burn, the mechanical properties of Zr-4 alloys are deteriorated obviously. The results provide a theoretical and experimental basis for technical optimization in the grinding of Zr-4 alloys with efficiency and high quality. Source

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